A device and method for monitoring particulate contamination of hydraulic fluid sampled from a drain valve.

Abstract

This invention discloses a device and method for monitoring (detecting) the particulate contamination level of hydraulic oil by sampling from a drain valve, belonging to the field of hydraulic oil monitoring (detection) technology. It includes a circulation loop and a monitoring (detection) loop. The circulation loop includes a check valve and a hydraulic pump for providing power. One end of the check valve is connected to one end of a first filter, and the other end is connected to the oil inlet of the hydraulic pump (the connection must not be reversed). The oil outlet of the hydraulic pump is connected to the oil filling filter in the oil tank via a third pipe fitting. The monitoring (detection) loop includes a contamination level monitoring (detection) instrument, which is connected in parallel to the circulation loop. By setting up the circulation loop, the hydraulic oil flow in the pipeline before the check valve can be in a sufficiently turbulent state, thereby thoroughly mixing the contaminants deposited at the bottom of the oil tank or near the drain valve. A liquid sample representing the particulate contamination level of the oil tank and even the entire hydraulic system can be obtained at the drain valve.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic fluid monitoring technology, and more specifically, relates to a device for monitoring the particulate contamination of hydraulic fluid sampled from a drain valve. Background Technology

[0002] In hydraulic systems, power is transmitted and controlled via hydraulic fluid in a closed circuit. Hydraulic fluid serves as both a lubricant and a power transmission medium. The presence of solid particulate contaminants in hydraulic fluid not only hinders its lubrication performance but also leads to component wear and even malfunction. The degree of solid particulate contamination in hydraulic fluid is closely related to the performance of the hydraulic system, such as reliability and durability; therefore, the contamination level should be controlled within the permissible range for the hydraulic system. However, this requires real-time or periodic monitoring of the hydraulic fluid.

[0003] In hydraulic fluid monitoring, how to extract or collect fluid samples (hereinafter referred to as sampling) is a key aspect of hydraulic fluid monitoring technology. Although GB / T 17489—1998 "Analysis of Hydraulic Particulate Contamination: Extraction of Fluid Samples from Working System Pipelines" states that "the best method is to extract fluid samples from a main pipeline of a working hydraulic system", there are indeed many difficulties in actual operation.

[0004] Some existing hydraulic systems are not designed with sampling valves, making it impossible to sample from their main pipelines. Even if sampling valves are installed, sampling from hydraulic lines operating at pressures above 5 MPa is dangerous, especially from high-pressure lines, which pose risks such as jetting and hose whipping. Furthermore, there are ultra-high-pressure hydraulic systems exceeding 100 MPa. A more practical problem is that operating hydraulic machinery and its hydraulic systems (including oil tanks) are typically inaccessible. For example, according to GB 28241—2012 "Safety Technical Requirements for Hydraulic Presses," except for hydraulic presses used for head forming and ship plate forming where protective devices are not recommended, most other hydraulic presses are designed with fixed, enclosed protective devices and / or photoelectric protection devices to prevent personnel from entering the danger zone. If any personnel, including sampling and analysis personnel, enter the danger zone, it may trigger an alarm and an emergency shutdown of the hydraulic press. Although alternative sampling methods specified in GB / T 17489—1998 include "extracting liquid samples from the oil tank of a working hydraulic system" and the sampling and analysis procedures for extracting samples from the oil tank specified in GB / T 37162.1—2018 "Monitoring of particulate contamination of hydraulic transmission fluids - Part 1: General Rules", these methods also have operational difficulties or are even impossible to implement.

[0005] Even when hydraulic fluid is flowing within the tank, the tank's structure inherently allows for the settling of heavier contaminants, preventing particulate contaminants from being evenly distributed throughout the tank. GB / T37162.1—2018 stipulates that "before sampling from a stationary container, the container should be thoroughly shaken to ensure the liquid is evenly mixed." However, this "shaking method" is not feasible for hydraulic tanks. In this state, the hydraulic fluid is not in a turbulent flow, thus particulate contaminants cannot be evenly distributed throughout the hydraulic fluid, leading to inaccurate and unreliable results from contaminant monitoring instruments. Summary of the Invention

[0006] 1. The problem to be solved

[0007] To address the problem in existing monitoring devices where hydraulic fluid is directly sampled from the tank at the sampling point, resulting in uneven distribution of particulate contaminants throughout the hydraulic fluid and inaccurate monitoring results, this disclosure provides a hydraulic fluid particulate contamination monitoring device and method that samples from the drain valve. By setting up a circulation loop, the hydraulic fluid in the pipeline before the check valve can flow and be in a fully turbulent state, thereby thoroughly mixing the contaminants settled at the bottom of the tank or near the drain valve. A liquid sample representing the particulate contamination of the tank and even the entire hydraulic system can be obtained at the drain valve, and then monitored by a contamination monitoring instrument, ensuring the accuracy and reliability of the contamination monitoring results and reducing the risk of misjudgment.

[0008] 2. Technical Solution

[0009] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0010] The first aspect of this invention provides a method for monitoring the particulate contamination level of hydraulic oil sampled from a drain valve, comprising:

[0011] Sampling: Obtain the hydraulic fluid to be monitored from the drain valve on the oil tank;

[0012] Circulation: The hydraulic oil is introduced into a circulation loop connected to the drain valve, and the hydraulic oil is made to flow in the circulation loop in a turbulent state by a servo motor driving the hydraulic pump.

[0013] Monitoring: The contamination level of the hydraulic fluid at a specified location in the circulation loop is monitored by a contamination monitoring instrument connected in parallel to the circulation loop.

[0014] In some embodiments, a filtration step is further included between the circulation step and the monitoring step, wherein the filtration step filters the hydraulic oil through a filter connected in series in the circulation loop.

[0015] In some embodiments, the sampling step may further include: running the hydraulic fluid in the tank in the hydraulic system for at least a second time threshold before sampling from the drain valve on the tank.

[0016] In some embodiments, during the cyclic steps;

[0017] (1) Control the servo motor to make the hydraulic pump operate at a first time threshold with a flow rate lower than a first threshold flow rate; wherein the first threshold flow rate is lower than the turbulent flow rate in the circulation loop;

[0018] (2) Control the servo motor to make the hydraulic pump run at a second time threshold with a flow rate higher than the second threshold flow rate; wherein the second threshold flow rate is greater than the turbulent flow rate in the circulation loop.

[0019] In some embodiments, the filtration step includes: monitoring the pressure difference of the hydraulic oil in the filter using a pressure gauge; when the pressure difference value of one or two filters exceeds a threshold and the signal pressure drop is not reached, continuing the cyclic filtration step.

[0020] In some embodiments, the contamination monitoring instrument uses an automatic particle counting method to monitor the contamination level of the hydraulic fluid.

[0021] A second aspect of the present invention provides a hydraulic oil particulate contamination monitoring device for sampling from a drain valve, comprising: a circulation loop including a check valve and a hydraulic pump for providing power, wherein one end of the check valve is connected to a drain valve on an oil tank via a first fitting, and the other end is connected to the oil inlet of the hydraulic pump, and the oil outlet of the hydraulic pump is connected to an oil filter in the oil tank; and

[0022] The monitoring loop includes a contamination monitoring instrument connected in parallel to the circulation loop for monitoring the contamination level of the hydraulic fluid at a designated location within the circulation loop. By setting up the circulation loop, the hydraulic fluid flow in the pipeline before the check valve is kept in a sufficiently turbulent state, thereby thoroughly mixing any contaminants deposited at the bottom of the tank or near the drain valve. A representative fluid sample can then be obtained at the drain valve and monitored by the contamination monitoring instrument, improving the accuracy of the contamination monitoring results and reducing the likelihood of misjudgment.

[0023] In some embodiments, the monitoring circuit further includes a first shut-off valve and a third shut-off valve. The oil inlet of the contamination monitoring instrument is connected to the first pipe fitting through the first shut-off valve, and the oil outlet of the contamination monitoring instrument is connected to the third pipe fitting through the third shut-off valve. By setting the first shut-off valve and the third shut-off valve, when the hydraulic oil in the circulation circuit is flowing and mixing, oil that has not yet reached a turbulent state can be prevented from entering the contamination monitoring instrument, ensuring that the monitoring results are true and accurate.

[0024] In some embodiments, a second shut-off valve is provided on the first pipe fitting, the second shut-off valve being located near the check valve, and the first pipe fitting is connected to the drain valve via a quick-connect coupling with double check valves. The quick-connect coupling with double check valves allows the pipe near the drain valve to be disconnected after testing, thus preventing the inlet of the circulation pipe from receiving hydraulic fluid from the tank, reducing hydraulic fluid discharge to some extent. When the device is not monitoring, both ends of the quick-connect coupling 3 are disconnected, preventing external contaminants from entering the circuit.

[0025] In some embodiments, the circulation loop further includes a second fitting and a third fitting, the other end of the check valve being connected to the oil inlet of the hydraulic pump via the second fitting; the oil outlet of the hydraulic pump being connected to the oil filter in the oil tank via the third fitting, wherein a first filter is provided on the second fitting.

[0026] 3. Beneficial effects

[0027] The above-described one or more technical solutions in this application have at least one or more of the following technical effects:

[0028] (1) By setting up a circulation loop, the present invention can make the hydraulic oil in the circuit before the check valve flow and be in a fully turbulent state, so as to fully mix the contaminants settled at the bottom of the oil tank or near the drain valve. A representative liquid sample can be obtained at the drain valve and then monitored by a contamination monitoring instrument to ensure the accuracy of the contamination monitoring results and avoid misjudgment.

[0029] (2) By setting a first shut-off valve and a third shut-off valve, the present invention can prevent oil that has not yet reached a turbulent state from entering the contamination monitoring instrument when the hydraulic oil in the circulation loop is flowing and mixing, thus preventing the monitoring results from being true and accurate.

[0030] (3) The present invention is equipped with a quick-connect coupling with double check valves. After the test is completed, the pipeline near the drain valve can be disconnected. Then the oil inlet of the circulation pipeline will no longer receive hydraulic oil from the oil tank, which will reduce the discharge of hydraulic oil to a certain extent. When the device is not monitoring, both ends of the quick-connect coupling 3 are disconnected, which can prevent external contaminants from entering the circuit.

[0031] (4) By setting up a filter, the present invention can filter the hydraulic oil using a filter program, at least the part of the hydraulic oil at the bottom of the tank that is usually the most polluted. This not only effectively protects the testing instrument, but also avoids misjudgment caused by using the most polluted hydraulic oil as a sample.

[0032] (5) In this invention, the mounting plane of the built-in pump of the hydraulic pump and the contamination level measuring instrument is at basically the same height as the mounting plane of the oil tank, so that the oil suction port of the built-in pump of the hydraulic pump and the contamination level measuring instrument always maintains positive gauge pressure, eliminating the negative pressure (vacuum) generated by general "suction analysis" and the factors that cause monitoring errors.

[0033] (6) The method provided by this invention conforms to national standards, has specific operating procedures, and is highly instructive for specific operations. It can be uniformly adopted by those skilled in the art, is easy to promote, and achieves uniformity in monitoring and analysis schemes. This avoids the problems of inconsistent monitoring results and duplicate monitoring caused by different schemes used in reality. It greatly improves the efficiency of industry communication, transactions, and other aspects. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of sampling from an existing fuel tank.

[0035] Figure 2 This is a schematic diagram of sampling from an existing fuel tank.

[0036] Figure 3 This is a schematic diagram of a hydraulic oil particulate contamination monitoring device provided in an embodiment of the present invention;

[0037] Figure 4 This is a schematic flowchart of a method for monitoring the particulate contamination of hydraulic oil sampled from a drain valve, provided in an embodiment of the present invention.

[0038] In the picture:

[0039] a1. Low-pressure source; a2. Oil tank A; a3. Sampling bottle; a4. Flexible tube; a5. Sampler; a6. Cap;

[0040] b1. Fuel tank B; b2. Measuring instrument;

[0041] 100. Circulation loop; 200. Monitoring loop;

[0042] 1. Oil tank; 2. Drain valve; 3. Quick-connect coupling with double check valves; 4. Check valve; 5. First shut-off valve; 6. Second shut-off valve; 7. First filter; 8. Hydraulic pump; 9. Contamination monitoring instrument; 10. Servo motor; 11. Second filter; 12. Bypass check valve; 13. Pressure gauge switch; 14. Pressure gauge; 15. Third shut-off valve; 16. Hoses; 17. Oil filling filter; 20. First fitting; 21. Second fitting; 22. Third fitting; 23. Fourth fitting; 24. Fifth fitting. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0044] The present invention will be further described below with reference to specific embodiments.

[0045] Application Overview

[0046] In hydraulic fluid monitoring, how to extract or collect fluid samples (hereinafter referred to as sampling) is a key aspect of hydraulic fluid monitoring technology. Although GB / T 17489—1998 "Analysis of Hydraulic Particulate Contamination: Extraction of Fluid Samples from Working System Pipelines" states that "the best method is to extract fluid samples from a main pipeline of a working hydraulic system", there are indeed many difficulties in actual operation.

[0047] Some existing hydraulic systems are not designed with sampling valves, making it impossible to sample from their main pipelines. Even if sampling valves are installed, sampling from hydraulic lines operating at pressures above 5 MPa is dangerous, especially from high-pressure lines, which pose risks such as jetting and hose whipping. Furthermore, there are ultra-high-pressure hydraulic systems exceeding 100 MPa. A more practical problem is that operating hydraulic machinery and its hydraulic systems (including oil tanks) are typically inaccessible. For example, according to GB 28241—2012 "Safety Technical Requirements for Hydraulic Presses," except for hydraulic presses used for head forming and ship plate forming where protective devices are not recommended, most other hydraulic presses are designed with fixed, enclosed protective devices and / or photoelectric protection devices to prevent personnel from entering the danger zone. If any personnel, including sampling and analysis personnel, enter the danger zone, it may trigger an alarm and an emergency shutdown of the hydraulic press. Although alternative sampling methods specified in GB / T 17489—1998 include "extracting liquid samples from the oil tank of a working hydraulic system" and the sampling and analysis procedures for extracting samples from the oil tank specified in GB / T 37162.1—2018 "Monitoring of particulate contamination of hydraulic transmission fluids - Part 1: General Rules", these methods also have operational difficulties or are even impossible to implement.

[0048] For example, YB / T 4629—2017 "Guide to Hydraulic Oil Change for Metallurgical Equipment L-HM Hydraulic Oil" also stipulates: "4 Sampling 4.1 For the working system, samples shall be taken at: c) the sampling point in the oil tank according to the actual situation." However, its normative reference standards do not contain standards regarding sampling, so the sampling shall be temporarily assumed to comply with GB / T 17489—1998. Similarly, GJB 380.7A—2015 "Contamination Testing of Aviation Working Fluids Part 7: Method for Collecting Liquid Samples from the Tank" specifies the method for collecting liquid samples from the tank, but does not stipulate that the tank must be in operation. Therefore, the provisions of this standard are more conducive to practical operation.

[0049] Furthermore, inconsistencies in sampling methods and procedures within the oil tank can lead to monitoring results that cannot be jointly confirmed by both parties or certified by a third party. This often results in wasted manpower and resources, increased manufacturing costs, and delayed product delivery and use. Repeated sample submissions, re-cleaning and reassembling of hydraulic components and systems, prolonged or repeated flushing of the hydraulic system, and even replacement of hydraulic fluid have occurred more than once in previous operations. Therefore, obtaining representative liquid samples according to relevant standards and specifications to ensure accurate and reliable monitoring results is of significant practical value.

[0050] According to GB / T 3766—2015 "General Rules and Safety Requirements for Hydraulic Transmission Systems and Their Components", oil tanks should have an oil filling point (port) and a drain device (drain valve). GB / T 17489—1998 specifies: "4.2 Sampling from the oil tank 4.2.2 Take a sample from a central area where the oil is flowing and away from areas of stillness caused by corners or partitions. In section 4.2.3, such as..." Figure 1 As shown, an opening is selected in the oil tank Aa2 above the liquid level. A sampler can be inserted through this opening. One end of the sampler is installed in the oil tank Aa2 via a flexible tube a4. A welded plug is installed on the sampler. A cap a6 is fitted onto the sampling bottle a3. The cap a6 is a special cap adapted to the sampled oil and a low-pressure source a1 is installed on the cap a6. The distance h / 2 is calculated to determine the sampling point to be located below the liquid level depth of h / 2.

[0051] GB / T 37162.1—2018 specifies: "6.3 Offline Sampling 6.3.7 Sampling should not be taken from the drain valve port. 6.6 Aspiration Analysis from Tank or Container 6.6.1 Sampling should be taken from the location where the liquid flows." This standard specifies four sampling and analysis methods (mainline, online, offline, and aspiration). The aspiration analysis method is described in [link to relevant documentation]. Figure 2 Appendix A (Informative Appendix) of GB / T 37162.1—2018 describes: [Example of Appendix A] Figure 2As shown, the measuring instrument b2 used for suction analysis is mainly used for liquid analysis in non-pressure vessels, such as oil drums Bb1 or system tanks. Based on the interpretation of this standard, it should be stated as: "Suction analysis using a contamination monitoring device is mainly used for liquid analysis in non-pressure vessels, such as oil drums or system tanks." This is because "using a contamination monitoring device" is the main difference between "suction analysis" and "offline analysis" specified in this standard. Therefore, it is determined that sampling from the tank as specified in GB / T 17489—1998 is for "offline analysis," but its recommended sampling method is also "suction."

[0052] Both of the above standards require that the hydraulic fluid in the tank be flowing during sampling, i.e., the hydraulic system and its tank be operational; and require that the opening on the top cover of the tank be opened to allow the flexible tubing and / or sampler to extend into the hydraulic fluid inside the tank. However, in GB / T 37162.1—2018, if... Figure 2 The image shows suction at the liquid surface, not suction at a depth below the liquid surface, which is clearly problematic. Both standards specify or recommend suction as the sampling method; the difference lies in GB / T 37162.1—2018, which recommends suction using a pump built into the contamination monitoring device.

[0053] Based on a comparison of the similarities and differences between GB / T 17489—1998 and GB / T 37162.1—2018, further analysis reveals the following debatable issues with both standards:

[0054] 1) Even when hydraulic fluid is flowing in the tank, the tank's structure inherently allows for the settling of heavy contaminants, preventing particulate contaminants from being evenly distributed throughout the tank. GB / T37162.1—2018 stipulates that "before sampling from a stationary container, the container should be thoroughly shaken to ensure the liquid is evenly mixed." However, this "shaking method" is not feasible for hydraulic tanks.

[0055] 2) GB / T 3766—2015 does not specify that a sampling port must be provided on the top cover of the fuel tank. If the top cover of the fuel tank does not have a sampling port that conforms to the requirements of GB / T 17489—1998, then the most likely opening is the mounting hole of the air filter, i.e., the oil filler port. Opening the oil filler port may allow external contaminants to enter the fuel tank, especially the mounting hole of the air filter without a flange; moreover, the mounting hole of the air filter is usually located at the corner of the top cover of the fuel tank, and this opening position generally does not comply with the requirements of Clause 4.2.2 of GB / T 17489—1998 (see above).

[0056] 3) GB / T 17489—1998 stipulates that "a reference mark shall be set on the sampler to indicate the oil level in the tank at the insertion point." This is not necessarily feasible. One problem is how to observe this reference mark at the oil filler port. Another problem is that the sampler is connected to a flexible tube and the hydraulic fluid is required to be flowing, so the sampler and the mark on it may change at any time.

[0057] 4) As described in Appendix A (informative appendix) of GB / T 37162.1—2018, aspiration analysis requires the transfer of liquid sample from the container to the sensor (e.g., via a built-in pump), which is a source of error. When a pump is used to lift the liquid into the instrument, a negative pressure (vacuum) is created, drawing air from the liquid or pipe fittings. Air bubbles in the analyzed liquid will affect the instrument's monitoring and introduce errors. If the pump is located upstream of the sensor, additional particles generated during pump operation will introduce additional errors, resulting in unrepresentative test data.

[0058] 5) Note 1 of Clause 4.2.8 in GB / T 17489—1998 states: "When a procedure for dispersing particulate contaminants has been determined for a specific system, that procedure should be maintained for all similar systems." This note indicates that GB / T 17489—1998 does not specify a procedure for "dispersing particulate contaminants as uniformly as possible throughout the tank," thus introducing significant uncertainty in sampling and analysis. GB / T 17489—1998 considers the flowing hydraulic fluid in the tank to be conducive to the "uniform dispersion" of particulate contaminants. However, according to the tank design requirements specified in GB / T 3766—2015, "the hydraulic fluid in the tank should circulate at a low speed to allow the release of entrained gases and the sedimentation of heavy contaminants." In actual use, the flow of hydraulic fluid in tanks directly contradicts the expectations of this standard in GB / T 17489—1998. Since the flow of hydraulic fluid in the tank does not "distribute particulate contaminants as evenly as possible throughout the tank," it is unnecessary to require sampling while the hydraulic system and its tank are in operation. Moreover, the sampling methods and procedures specified in the two standards above are difficult to implement.

[0059] Furthermore, based on practical experience, the following requirements are set for sampling points in GJB 380.7A—2015: "4.2 Sampling Point Setup: a) When the liquid tank only has an injection port, sample at the injection port; b) When the liquid tank has both an injection port and a drain valve, sample at the drain valve; d) In special liquid tanks, the sampling location shall be determined by the designer, and the location of the sampling point should be representative of the true contamination state of the working fluid in the liquid tank." This is relatively easy to operate. However, GB / T 37162.1—2018 does not recommend sampling from the drain valve port, which is inconsistent with the requirements of GJB 380.7A—2015. This is a problem of inconsistent standards that urgently needs to be addressed.

[0060] Example 1

[0061] Embodiments of this disclosure provide a hydraulic fluid particulate contamination monitoring device to solve or at least partially solve the above-mentioned problems. Reference will now be made to... Figure 1 The following describes some example embodiments. Note that in the following description, "hydraulic fluid" may be used as a sample to be monitored. However, the scope of this disclosure is not limited thereto, and any monitoring device that can be employed as described herein is covered within the scope of this disclosure.

[0062] Embodiments of this disclosure provide a device for monitoring the particulate contamination of hydraulic fluid sampled from a drain valve, in order to solve or at least partially solve the aforementioned problems. Reference will now be made to... Figure 1 The following describes some example embodiments. Note that in the following description, "hydraulic fluid" may be used as a sample to be monitored. However, the scope of this disclosure is not limited thereto, and any monitoring device that can be employed as described herein is covered within the scope of this disclosure.

[0063] like Figure 1 As shown, the hydraulic fluid particulate contamination monitoring device according to embodiments of the present disclosure generally includes a circulation loop 100 and a monitoring loop 200.

[0064] The circulation loop 100 includes a one-way valve 4 and a hydraulic pump 8 for providing power, which is driven by a servo motor 10. One end of the one-way valve 4 is connected to the drain valve 2 on the oil tank 1 via a first fitting 20, and the other end is connected to the oil inlet of the hydraulic pump 8 via a second fitting 21. The oil outlet of the hydraulic pump 8 is connected to the oil filling filter 17 in the oil tank 1 via a third fitting 22. Preferably, the third fitting 22 is connected to the oil filling filter 17 in the oil tank 1 via a hose 16. In one possible embodiment, a dedicated air filter with a rigid tube is used instead of the oil filling filter 17 and the rigid tube under the hose 16, allowing the rigid tube to be inserted below the lowest liquid level in the oil tank, and a diffuser or defoamer can be installed at the end of the rigid tube.

[0065] The monitoring loop 200 includes a contamination monitoring instrument 9, which is connected in parallel to the circulation loop 100 to monitor the contamination level of the hydraulic oil at a designated location on the circulation loop 100. By setting up the circulation loop 100, the hydraulic oil flow in the pipeline before the check valve 4 can be kept in a fully turbulent state, thereby thoroughly mixing the contaminants deposited at the bottom of the oil tank or near the drain valve 2. A representative liquid sample can be obtained at the drain valve 2, and then monitored by the contamination monitoring instrument 9, improving the accuracy of the contamination monitoring results and reducing the likelihood of misjudgment.

[0066] In some embodiments, the monitoring circuit 200 further includes a first shut-off valve 5 and a third shut-off valve 15. The oil inlet of the contamination monitoring instrument 9 is connected in series with the first pipe fitting 20 through the first shut-off valve 5. A section of rigid pipe connected to the first shut-off valve 5 is connected in parallel to the rigid pipe between the quick-connect fitting 3 with double check valves and the check valve 4. The connection point (sampling point) between the rigid pipe and the first pipe fitting 20 conforms to GB / T 17489—1998. Further, the diameter of the "section of rigid pipe connected to the first shut-off valve 5" is [a fraction of the diameter of the first pipe fitting between the quick-connect fitting 3 with double check valves and the check valve 4]. d / 4~ d / 3, and the inner diameter of "a section of rigid pipe connected to the first shut-off valve 5" is within φ 1.2mm~ φ Within a 5.0mm range. The oil outlet of the contamination monitoring instrument 9 is connected to one end of the third shut-off valve 15, and the other end of the third shut-off valve 15 is connected to a section of rigid pipe before the hose 16. The contamination monitoring instrument 9 has a built-in pump with a suction function. The hydraulic oil drawn from the sampling point is counted by the contamination monitoring instrument 9 and then discharged back into the oil tank 1 through the hose 16 and the oil filler 17 on the oil tank. In this example, by setting the first shut-off valve 5 and the third shut-off valve 15, when the hydraulic oil in the circulation loop 100 is flowing and mixing, it can prevent oil that has not yet reached a turbulent state from entering the contamination monitoring instrument, ensuring that the monitoring results are true and accurate. It should be noted that the first shut-off valve 5, the third shut-off valve 15 and the second shut-off valve 6 can be manual shut-off valves or solenoid valves. In this embodiment, a manual shut-off valve is selected, and the manual shut-off valve has a switch indicator and signal.

[0067] In some embodiments, a second shut-off valve 6 is provided on the first pipe fitting 20, located near the one-way valve 4, and the first pipe fitting 20 is connected to the drain valve 2 via a quick-connect fitting 3 with double one-way valves. The front end of the quick-connect fitting 3 with double one-way valves is connected to the drain valve 2 via a flexible hose. The inner diameter of the hose should be compatible with the drain valve 2 connection on the oil tank, and appropriate sealing measures should be used to lock the hose and drain valve 2 connection tightly, preventing them from falling off or leaking air. The quick-connect fitting 3 with double one-way valves allows the pipe near the drain valve to be disconnected after the test, so that the oil inlet of the circulation pipe no longer receives hydraulic oil from the oil tank, reducing the outflow of hydraulic oil to a certain extent. When the device is not monitoring, both ends of the quick-connect fitting 3 are disconnected, preventing external contaminants from entering the circuit.

[0068] In some embodiments, the quick-connect fitting 3 with dual check valves, the check valve 4, the shut-off valve 6, and the shut-off valve 6 are connected by a rigid pipe, that is, the first pipe fitting is a rigid pipe, and the inner diameter of the rigid pipe connecting the quick-connect fitting 3 with dual check valves and the check valve 4 is [missing information]. φd It is the Reynolds number Re Users should not change the calculated parameters under normal circumstances, otherwise it cannot be guaranteed that the sampling point is in a fully turbulent state.

[0069] In some embodiments, a first filter 7 is provided on the second pipe fitting 21; a second filter 11 is also provided on the third pipe fitting 22. In this embodiment, both the first filter 7 and the second filter 11 are filters with manual switching function. When filtration is not required, they are both adjusted to non-working mode, at which time both the first filter 7 and the second filter 11 are in the open state. When it is determined that there are many contaminants in the oil tank, they can be opened, which can effectively protect the contamination monitoring instrument, prevent the contamination monitoring result from exceeding the maximum range, and avoid misjudgment of subsequent measurements caused by using the most contaminated hydraulic oil as the liquid sample. It should be noted that the filter with manual switching function is an assembly, and the filter element in it should be new each time it is used and is generally relatively coarse (>65μm). One end of the first filter 7 is connected to the one-way valve 4, and the other end is connected to the oil inlet of the hydraulic pump 8. It must not be installed backwards.

[0070] In some embodiments, a bypass check valve 12 is connected in parallel to the second filter 11. One end of the bypass check valve is connected to the oil inlet side of the third pipe near the second filter 11 via a fourth pipe fitting 23, and the other end of the bypass check valve is connected to the oil outlet side of the third pipe fitting near the second filter via a fifth pipe fitting 24. The bypass check valve 12 is connected in parallel with the second filter 11, serving as a bypass valve for the second filter 11 and a safety valve for the entire monitoring device.

[0071] In some embodiments, the fourth pipe fitting 23 has an extension pipe fitting 231, on which a pressure gauge switch 13 and a pressure gauge 14 are provided. The pressure gauge 14 is used to monitor the pressure at the inlet of the hydraulic pump 8.

[0072] It should be noted that, as described in Appendix A (informative appendix) of GB / T 37162.1—2018, the suction analysis method requires the liquid sample to be transported from the container to the sensor (e.g., via a built-in pump), which is a source of error. When a pump is used to lift the liquid into the instrument, a negative pressure (vacuum) is generated, drawing air from the liquid or pipe joints. Air bubbles in the analyzed liquid will affect the instrument's monitoring and introduce errors. If the pump is located upstream of the sensor, additional particles generated during pump operation will introduce additional errors, making the test monitoring results unrepresentative. In this embodiment, preferably, the mounting planes of the hydraulic pump and the built-in pump of the contamination measuring instrument are at substantially the same height as the oil tank mounting plane, ensuring that the oil inlet of the hydraulic pump and the built-in pump of the contamination measuring instrument always maintains positive gauge pressure, eliminating the negative pressure (vacuum) factor that causes monitoring errors in general "suction analysis".

[0073] Example 2

[0074] like Figure 4 As shown, embodiments of this disclosure provide a method for monitoring the particulate contamination level of hydraulic fluid sampled from a drain valve. Those skilled in the art should understand that this embodiment is described using the monitoring device provided in Embodiment 1, but is not limited thereto. The method includes:

[0075] S1: Sampling: Obtain the hydraulic fluid to be monitored from the drain valve on the oil tank. Specifically, after assembling the monitoring device in Example 1, sampling is performed according to the following steps. See S11-S14 for specific steps.

[0076] S11: Clean the interface of drain valve 2 and quick-connect fitting 3 with double check valve.

[0077] Specifically, clean the interface of drain valve 2 and the interface of the double one-way valve quick-connect fitting 3 (one end) with a lint-free cleaning cloth or cleaning solution, and open the dust cap. Similarly, clean the exposed surface of the air filter and its surroundings, as well as the rigid pipe connected to the hose 16 below, and open the dust cap. The air filter here is an inherent device on the fuel tank and will not be described in detail here.

[0078] S12: Connect the two ends of the quick-connect fitting 3 with double check valves through hoses, and then connect the quick-connect fitting 3 with double check valves to the drain valve 2.

[0079] S13: Open drain valve 2 to release the waste hydraulic oil.

[0080] Specifically, open drain valve 2 to release the hydraulic oil between drain valve 2 and quick-connect coupling 3 with double check valves, then close drain valve 2. The released hydraulic oil can only be treated as waste oil and disposed of in accordance with environmental protection requirements.

[0081] Optionally, open drain valve 2, extract a certain amount of hydraulic oil using a clean, transparent sampling bottle, and then close drain valve 2. Visually assess the degree of contamination according to relevant standards such as NB / SH / T 0599—2013 "L-HM Hydraulic Oil Change Index," or use the "automatic particle counter" specified in GB / T 37163—2018 "Automatic Particle Counting Method for Hydraulic Transmission Using the Principle of Light Shielding to Determine the Particulate Contamination of Liquid Samples" to measure the hydraulic oil in the sampling bottle.

[0082] S14: Remove the upper part of the air filter from oil tank 1, connect hose 16 in the monitoring device to oil filler filter 17, and complete the connection between the overall structure of the monitoring device and oil tank 1. Remove a section of hose with a double check valve quick-connect coupling 3, and connect the corresponding end of the "hydraulic oil particulate contamination monitoring device" in Example 1 to it; remove the upper part of the air filter, and connect the corresponding end of the "hydraulic oil particulate contamination monitoring device" with the same upper part of the air filter to oil filler filter 17.

[0083] For safety reasons, this embodiment is based primarily on the GJB 380.7A—2015 standard. Sampling and analysis of the drain valve should begin immediately after the hydraulic system and its tank have stopped operating. It should be noted that although GJB380.7A—2015 specifies a "drain valve sampling procedure," its requirement that "the working fluid should be agitated appropriately before sampling, and sampling should be carried out while contaminants are in suspension" makes it difficult to operate consistently and obtain representative samples. However, if the tank has not been used for a long time, contaminants such as solid particles, gels, and sludge (precipitates or residues smaller than 3μm from oxidized mineral oil) in the hydraulic fluid will concentrate and settle at the bottom of the tank. For tanks with large volumes, it is difficult to achieve uniform mixing of the hydraulic fluid throughout the entire tank using only a "hydraulic fluid particle contamination monitoring (detection) device that samples from the drain valve."

[0084] Therefore, in some embodiments, the sampling step further includes: allowing the hydraulic fluid in the tank to operate normally in the hydraulic system for at least a second time threshold before sampling from the drain valve on the tank. Preferably, the sampled fluid must also meet the "health and safety" requirements specified in standards such as GB / T 37162.1—2018. It should be noted that sampling and analysis from a tank that has just stopped operating is the most feasible and easiest to be universally accepted and agreed upon by all parties; otherwise, the fluid sample cannot represent the true contamination state of the hydraulic system. In this embodiment, the second time threshold is 24 hours.

[0085] S2: Circulation: Turn on the power to the servo motor 10, start the servo motor 10 and hydraulic pump 8, introduce hydraulic oil into the circulation loop connected to the drain valve, and drive the hydraulic pump through the servo motor to make the hydraulic oil flow in the circulation loop to form a turbulent state. When the filtration step is not performed, switch the first filter 7 and the second filter 11 with manual switching function to the straight-through loop and start the oil circulation.

[0086] Preferably, (1) the servo motor is controlled to make the hydraulic pump operate at a first time threshold with a flow rate lower than a first threshold flow rate; wherein the first threshold flow rate is lower than the turbulent flow rate in the circulation loop; in this embodiment, the first threshold flow rate is the Reynolds number. Re The value is 2300, and the first time threshold is 10 minutes. During this process, it is necessary to observe whether there are any abnormalities in the loop 200. If so, stop the machine for inspection and handling; if not, continue to the next step.

[0087] (2) Control the servo motor to make the hydraulic pump operate at a second time threshold with a flow rate higher than the second threshold flow rate; wherein the second threshold flow rate is greater than or equal to the turbulent flow rate in the circulation loop. In this embodiment, the second time threshold is 30 min, and the second threshold flow rate Reynolds number is... Re The value is 4000. It should be noted that the turbulent flow rate in the circulation loop is related to the inner diameter of the first pipe connecting the quick-connect fitting 3 with double check valves and the check valve 4. φd Related, inner diameter φd The turbulent flow rates differ depending on the type of filter. To ensure sufficient turbulence at the sampling point, users should generally not replace the first tube 20 themselves. If any filter alarms, all filters should be replaced with new filter cartridges.

[0088] S3: Monitoring: The contamination level of the hydraulic fluid at a designated location in the circulation loop is monitored using a contamination monitoring instrument 9 connected in parallel to the circulation loop. When there is no significant change in the differential pressure between the filters, the first shut-off valve 5 and the third shut-off valve 15 are opened, and the contamination monitoring instrument 9 is activated for monitoring. In some embodiments, the contamination monitoring instrument uses an automatic particle counting method to monitor the hydraulic fluid. The intended use and desired accuracy of the measurement data from the contamination monitoring instrument 9 determine the selected analytical method and the required precision of the monitoring instrument.

[0089] Confirmation of monitoring results in this embodiment:

[0090] ① Continue monitoring until the monitoring data of two consecutive liquid samples meet one of the following conditions:

[0091] a) The monitoring results are within the allowable range set by the pollution monitoring instrument manufacturer;

[0092] b) If the monitoring result is the number of particles, then the difference between the monitoring results of the two liquid samples is less than 10% at the smallest particle size monitored;

[0093] c) The contamination level is the same as that specified in GB / T 14039—2002 "Code for Solid Particle Contamination Level of Hydraulic Transmission Oil" or other standards;

[0094] ② Co-sign the monitoring report in accordance with the standards and regulations you are required to follow.

[0095] After monitoring is complete, check and confirm the closed status of drain valve 2 and shut-off valve. If they are indeed closed, pull out the rigid end of hose 16, put on a dust cap, and then put it back into the device. Reassemble the upper and lower oil filler filters of the original air filter (restore them). Disconnect the quick-connect coupling 3 with double check valves and put it back into the device. Then remove the hydraulic oil particulate contamination monitoring device from the safety protection area of ​​the hydraulic machinery. Restore the fixed closed protective device and / or photoelectric protection device, etc. In addition, it is not recommended to use the hydraulic oil particulate contamination monitoring device for long-term sampling and analysis of hydraulic oil in the tank, or to use the device as a bypass regeneration filter device.

[0096] It should be noted that the pollution level monitoring instrument 9 can be selected according to the analysis methods listed in Table 1, and Table 1 does not include other analysis methods that take samples from the shut-off valve 6.

[0097] Table 1. Sampling Analysis Methods for Pollution Monitoring Instruments

[0098]

[0099] It should also be noted that GB / T 37162.1—2018 does not recommend sampling from the drain valve port. According to this standard, those skilled in the art would generally not think of sampling from the drain valve port, which is a technical bias. In addition, GB / T 17489—1998 states that the hydraulic fluid flowing in the tank is conducive to the "uniform distribution" of particulate contaminants. However, due to the structure of the tank itself, it is impossible for the oil to achieve a turbulent state within the tank. Based on this, the applicant has creatively set up a circulation loop outside the tank, which allows the hydraulic fluid in the pipeline before the check valve to flow and be in a fully turbulent state. This ensures that the contaminants settled at the bottom of the tank or near the drain valve are fully mixed and uniform. A liquid sample representative of the tank and even the entire hydraulic system can be obtained at the drain valve, and then monitored by a contamination monitoring instrument to ensure the authenticity and accuracy of the contamination monitoring data and to avoid misjudgment.

[0100] In some embodiments, an S4 filtration step is further included between the circulation step and the monitoring step, wherein the filtration step filters the hydraulic fluid through a filter connected in series in the circulation loop. Here, the use of a filter or the absence of a filter can be selected according to the agreement between the monitoring party and the monitored party.

[0101] Before performing the filtration step, check that the first shut-off valve 5, the second shut-off valve 6, and the third shut-off valve 15 are closed, and open the drain valve 2. Furthermore, all filter elements should be new and have a particle size [μm(c)] corresponding to the filtration ratio of the filters in the monitoring device. Specifically, during the filtration step, switch the first filter 7 and the second filter 11 (with manual switching function) to the filter circuit and begin the following operations.

[0102] In some embodiments, during filtration, the pressure difference of the hydraulic oil in the filter is monitored by a pressure gauge. When the pressure difference value of one or two filters exceeds a threshold and the signal pressure drop is not reached, the cyclic filtration step continues for 30 minutes.

[0103] Furthermore, if the following situations are found during continued filtering, the following actions should be taken as agreed upon by the monitoring party and the monitored party: sampling and analysis operations should be stopped immediately, and sampling and analysis records should be made.

[0104] ① If, after continuing the filtration cycle for 30 minutes, the pollution level monitoring instrument 9 is started for monitoring, one or two transmitters will start to alarm; it should be noted that the transmitter here is an existing device on the filter, used to send electrical signals, audible and visual alarm signals, etc. when the filter is clogged.

[0105] ② If one or two transmitters start alarming before 30 minutes have elapsed while the cyclic filtering continues.

[0106] ③ If the pressure difference between one or two filters continues to increase significantly after 30 minutes of continuous filtration, but they have not yet reached the signal drop pressure.

[0107] It should be noted that, due to the special nature of fuel tank sampling, a filtration step should be selected before the monitoring step. This can effectively protect the testing instruments and avoid misjudgment. If a filter alarm is triggered during the filtration process, all filters should be replaced with new filter elements.

[0108] In some embodiments, the hydraulic fluid can be filtered for 40 minutes, and then the first filter 7 and the second filter 11 with manual switching function can be switched to the straight-through circuit before sampling and analysis can begin. This process can monitor the hydraulic fluid for a long time, but a special filler filter should be used. Here, a special filler filter refers to a filler filter with an oil pipe passing through the bottom of the filler filter and inserted into the hydraulic fluid in the oil tank at least 300 mm below the fluid level, so that the rigid pipe under the hose 16 can be inserted below the lowest fluid level in the oil tank.

[0109] Finally, it must be emphasized that there is no practically feasible method or procedure in the current standards to guarantee the extraction of a liquid sample representing the true contamination state of the hydraulic system and the hydraulic oil in the tank from the oil tank or the drain valve on the oil tank. The "Method for Monitoring Particulate Contamination of Hydraulic Oil Sampling from Drain Valve" proposed in this application complies with the provisions of GJB 380.7A—2015 standard; it also complies with the "Principles of Oil Extraction" stipulated in GB / T 17489—1998 standard; and it complies with the procedures and precautions for "Obtaining Representative Liquid Samples" stipulated in GB / T37162.1—2018 standard, including compliance with the provisions of "offline sampling" and "absorption from oil tank or container".

[0110] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly attached to the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0111] It should also be noted that the terms "a" and "b" in the specification, claims, and drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0112] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A device for monitoring the particulate contamination level of hydraulic oil sampled from a drain valve, characterized in that, include: The circulation loop includes a check valve and a hydraulic pump for providing power; the hydraulic oil is introduced into the circulation loop connected to the drain valve, and the hydraulic pump is driven by a servo motor to make the hydraulic oil flow in the circulation loop to form a turbulent state. The servo motor is controlled to cause the hydraulic pump to operate at a first time threshold at a flow rate lower than a first threshold flow rate; wherein the first threshold flow rate is lower than the turbulent flow rate in the circulation loop. The servo motor is controlled to make the hydraulic pump operate at a second time threshold with a flow rate higher than the second threshold flow rate; wherein the second threshold flow rate is greater than the turbulent flow rate in the circulation loop. One end of the one-way valve is connected to the drain valve on the oil tank via a first pipe fitting, and the other end is connected to the oil inlet of the hydraulic pump. The oil outlet of the hydraulic pump is connected to the oil filter inside the oil tank. A monitoring loop includes a contamination monitoring instrument connected in parallel to the circulation loop for monitoring the contamination level of hydraulic fluid at a specified location on the circulation loop. The monitoring circuit also includes a first shut-off valve and a third shut-off valve. The oil inlet of the pollution monitoring instrument is connected to the first pipe fitting through the first shut-off valve, and the oil outlet of the pollution monitoring instrument is connected to the oil filter in the oil tank through the third shut-off valve. The first pipe fitting is provided with a second shut-off valve, which is located near the oil inlet of the check valve, and the first pipe fitting is connected to the drain valve through a quick-connect fitting with double check valves. The circulation loop further includes a second fitting and a third fitting. The other end of the check valve is connected to the oil inlet of the hydraulic pump through the second fitting. The oil outlet of the hydraulic pump is connected to the oil filter in the oil tank through the third fitting. The second fitting is equipped with a first filter. The third pipe fitting is equipped with a second filter; a bypass check valve is connected in parallel to the second filter, serving as a bypass valve for the second filter and a safety valve for the entire monitoring device. One end of the bypass check valve is connected to the oil inlet side of the third pipe near the second filter via a fourth pipe fitting, and the other end of the bypass check valve is connected to the oil outlet side of the third pipe near the second filter via a fifth pipe fitting; the fourth pipe fitting has an extension pipe fitting, and a pressure gauge is provided on the extension pipe fitting.

2. The method for monitoring the particulate contamination level of hydraulic oil sampled from a drain valve according to claim 1, characterized in that, include: Sampling steps: Obtain the hydraulic fluid to be monitored from the drain valve on the oil tank; Circulation step: The hydraulic oil is introduced into the circulation loop connected to the drain valve, and the hydraulic pump is driven by a servo motor to make the hydraulic oil flow in the circulation loop to form a turbulent state; In the specific cyclic steps described above; (1) Control the servo motor to make the hydraulic pump operate at a first time threshold with a flow rate lower than a first threshold flow rate; wherein the first threshold flow rate is lower than the turbulent flow rate in the circulation loop; (2) Control the servo motor to make the hydraulic pump operate at a second time threshold with a flow rate higher than the second threshold flow rate; wherein the second threshold flow rate is greater than the turbulent flow rate in the circulation loop; The filtration step occurs between the circulation step and the monitoring step; the hydraulic fluid is filtered by a filter connected in series in the circulation loop. Specifically, the filtration steps include: monitoring the pressure difference of the hydraulic oil in the filter using a pressure gauge; when the pressure difference value of one or two filters exceeds the threshold and the signal pressure drop is not reached, the cyclic filtration steps continue. Monitoring: The contamination level of the hydraulic fluid at a specified location in the circulation loop is monitored by a contamination monitoring instrument connected in parallel to the circulation loop.

3. The method for monitoring the particulate contamination level of hydraulic oil sampled from a drain valve according to claim 2, characterized in that, The sampling step includes, before which the hydraulic fluid in the tank is run in the hydraulic system for at least a second time threshold, and then a sample is taken from the drain valve on the tank.

4. The method for monitoring the particulate contamination of hydraulic oil sampled from a drain valve according to claim 2, characterized in that, The aforementioned contamination monitoring instrument uses an automatic particle counting method to monitor the contamination level of the hydraulic fluid.

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