Full-range oil liquid water content detection method, medium and device based on capacitive type

Abstract

The application provides a full-range oil liquid water content detection method, medium and equipment based on a capacitive type, and belongs to the technical field of oil liquid water content detection. The method comprises the following steps: measuring comprehensive capacitance values corresponding to the upper and lower layer dielectric constants and the total height of the oil liquid to be detected, respectively; splitting the comprehensive capacitance values into two sub-capacitance values corresponding to the upper and lower layer dielectric constants; combining the mapping relationship between the layer dielectric constants and the corresponding layer level, and solving the free water layer height of the lower layer dielectric segment and / or the emulsified water layer height of the upper layer dielectric segment; and calculating the comprehensive water content based on the free water layer height and / or the emulsified water layer height, the equivalent water content of the emulsified water layer corresponding to the second dielectric constant, and the total height. The application can improve the accuracy of oil liquid water content detection.

Description

Technical Field

[0001] This application relates to the field of oil moisture detection technology, and in particular to a capacitive full-range oil moisture detection method, medium and device. Background Technology

[0002] Moisture in hydraulic fluids is a significant factor leading to oil deterioration and equipment failure. The presence of moisture accelerates oil oxidation, reduces lubrication performance, causes equipment corrosion and wear, and in severe cases, may result in equipment failure. Therefore, accurate detection of water content in hydraulic fluids is of significant engineering importance.

[0003] Currently, the main methods for measuring the water content in oil include distillation, Karl Fischer method, conductivity method, capacitance method, microwave method, and infrared spectroscopy. Among these, distillation and Karl Fischer are offline sampling and detection methods, which cannot monitor the water content in oil in real time and are no longer suitable for the online detection needs in industrial settings.

[0004] Among online detection methods, conductivity methods are only applicable to substances whose conductivity is greatly affected by water content, limiting their applicability. Infrared and microwave methods are costly and easily affected by varying oil-water mixing states, leading to unstable detection errors. Capacitance methods are relatively mature, have a wide measurement range, and are low-cost, making them the most widely used in oil moisture detection.

[0005] The basic principle of capacitance method for detecting water content in oil is based on the significant difference in dielectric constants between oil and water. The equivalent dielectric constant of an oil-water mixture changes with water content, and the water content can be calculated by measuring the change in capacitance. Although capacitance method has been widely used in oil moisture detection, current technology still has the following shortcomings: (1) Limited ability to distinguish the forms of water. Water in oil can be classified into several forms according to its content and state of existence, such as dissolved water (water dissolved in oil in molecular form), emulsified water (water suspended in oil as tiny droplets to form an emulsion), and free water (water stratified and settled at the bottom of the oil). Different forms of water have different effects on oil performance and equipment operation, but most existing capacitance detection schemes can only provide a single output of total water content, making it difficult to distinguish the specific forms of water.

[0006] (2) Measurement failure in high water content stage. When free water stratification occurs in the oil, the detection of existing capacitive sensors will be affected by the distribution of water state, resulting in a large measurement error. More seriously, when the water content is too high, the detection signal will exceed the upper limit of the measurable range of the detection circuit, making it impossible to detect high water content.

[0007] In summary, the existing technology lacks a solution for detecting oil moisture content that can simultaneously detect dissolved water, emulsion water, and free water, and achieve accurate measurement across the entire range from low to high moisture content. Summary of the Invention

[0008] The purpose of this application is to provide a capacitive full-range oil moisture detection method, medium, and device to solve at least one of the above-mentioned technical problems.

[0009] In a first aspect, this application provides a capacitive full-range oil moisture detection method, the method being applied in an oil moisture detection module, the oil moisture detection module including an oil chamber and a detection probe located within the oil chamber, the detection probe integrating a liquid level sensing element, a first dielectric constant sensing element, and a second dielectric constant sensing element located above the first dielectric constant sensing element; the method includes: After the oil to be tested enters the oil cavity and reaches the preset liquid level in the oil cavity, the first dielectric constant of the lower medium of the oil to be tested is obtained by the first dielectric constant sensing element. The second dielectric constant of the upper medium of the oil under test is obtained by the second dielectric constant sensing element; The comprehensive capacitance value of the oil under test at the preset liquid level is obtained through the liquid level sensing element; The overall capacitance value is divided into a first sub-capacitance value contributed by the lower medium segment and a second sub-capacitance value contributed by the upper medium segment according to the total height corresponding to the preset liquid level. Based on the first mapping relationship between the first sub-capacitor value and the first dielectric constant, and the second mapping relationship between the second sub-capacitor value and the second dielectric constant, the height of the free water layer in the lower dielectric segment and / or the height of the emulsified water layer in the upper dielectric segment can be deduced. The overall water cut is calculated based on the height of the free water layer and / or the height of the emulsified water layer, the second dielectric constant, and the total height. The second dielectric constant reflects the equivalent water cut of the emulsified water layer of the upper medium of the oil to be tested.

[0010] Optionally, calculating the overall water cut based on the height of the free water layer and / or the height of the emulsified water layer, the second dielectric constant, and the total height includes: The volume of free water is calculated based on the height of the free water layer and the dimensions of the oil cavity; The equivalent water content of the emulsion water in the upper medium of the oil to be tested is determined based on the second dielectric constant, and the volume of emulsion water is determined by combining the space volume occupied by the upper medium of the oil to be tested in the oil cavity. The free water volume and the emulsified water volume are added together, and the overall water content is calculated based on the total oil volume in the oil cavity.

[0011] Optionally, before obtaining the first dielectric constant of the lower medium of the oil under test through the first dielectric constant sensing element, the method further includes: The oil to be tested is left to stand in the oil chamber for a preset time.

[0012] Optionally, before dividing the overall capacitance value into a first sub-capacitance value contributed by the lower medium segment and a second sub-capacitance value contributed by the upper medium segment according to the total height corresponding to the preset liquid level, the method further includes: Based on the first dielectric constant and / or the second dielectric constant, determine whether the water in the upper medium of the oil to be tested is emulsified water, and whether the water in the lower medium of the oil to be tested is free water. If so, then execute the step of splitting the comprehensive capacitance value into a first sub-capacitance value contributed by the lower medium segment and a second sub-capacitance value contributed by the upper medium segment according to the total height corresponding to the preset liquid level.

[0013] Optionally, determining whether the water in the upper medium of the oil to be tested is emulsified water and whether the water in the lower medium of the oil to be tested is free water based on the first dielectric constant and / or the second dielectric constant includes: When the first dielectric constant exceeds the second threshold and the second dielectric constant is less than the second threshold, it is determined that the water in the upper medium of the oil to be tested is emulsified water and the water in the lower medium of the oil to be tested is free water. Alternatively, when the difference between the first dielectric constant and the second dielectric constant exceeds the first threshold, it is determined that the water in the upper medium of the oil to be tested is emulsified water, and the water in the lower medium of the oil to be tested is free water. Alternatively, if the first dielectric constant and / or the second dielectric constant are less than the third threshold, it is determined that both the upper medium and the lower medium of the oil under test are dissolved water. Alternatively, if the first dielectric constant and / or the second dielectric constant are greater than the third threshold and less than the fourth threshold, it is determined that both the upper medium of the oil to be tested and the lower medium of the oil to be tested are emulsified water. Alternatively, when the second dielectric constant exceeds the second threshold, it is determined that the water in both the upper and lower layers of the oil being tested is free water.

[0014] Optionally, when both the upper and lower media of the oil to be tested are emulsified water, the overall water content is determined based on the mapping relationship between the second dielectric constant and the equivalent water content of the emulsified water layer.

[0015] Optionally, the first dielectric constant sensing element is disposed at the bottom of the detection probe, and the second dielectric constant sensing element is disposed in the detection probe at an alarm height, the alarm height corresponding to the height of the free water layer when the water content in the oil reaches a preset alarm value.

[0016] Optionally, the liquid level sensing element is laid along the length of the detection probe, and the liquid level sensing element covers the total height of the oil to be tested.

[0017] Optionally, the oil cavity has an oil inlet and an oil outlet, with the oil outlet being higher than the oil inlet.

[0018] Optionally, the detection probe also integrates a temperature-sensitive element and a humidity-sensitive element, wherein the humidity-sensitive element is located at a position no lower than that of the second dielectric constant-sensitive element.

[0019] Optionally, the temperature-sensitive element, humidity-sensitive element, first dielectric constant-sensitive element, and second dielectric constant-sensitive element are located on the first side of the signal transmission plate of the detection probe, and the liquid level-sensitive element is located on the second side of the signal transmission plate, with the second side opposite to the first side.

[0020] Optionally, the method further includes: when the first dielectric constant and / or the second dielectric constant is less than a third threshold, determining that both the upper medium of the oil to be tested and the lower medium of the oil to be tested are dissolved water; Obtain the water activity value measured by the humidity-sensitive element; Obtain the temperature value measured by the temperature-sensitive element; The water activity value and the temperature value are input into a preset water calculation model based on the principle of solution thermodynamic equilibrium to calculate the overall water content.

[0021] In a second aspect, this application provides a computer-readable storage medium storing executable instructions that, when executed by a processor, cause the processor to perform the method described in any embodiment of this application.

[0022] In a third aspect, this application provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs, which, when executed by the one or more processors, cause the one or more processors to perform the method described in any embodiment of this application.

[0023] The capacitive full-range oil moisture detection method, medium, and equipment in this application have the following beneficial effects: First, by measuring different forms of moisture separately after static stratification and then uniformly converting the results, the coupling interference of moisture form distribution on the capacitive measurement results is avoided, ensuring that the moisture content in the high-water-content stage (when free water stratification occurs) can still be accurately measured. This overcomes the limitations of traditional capacitive methods, which suffer from large measurement errors when free water stratifies and fail when exceeding the detection range at high water content. Second, by using a liquid level sensing element to cover the total height and combining the dielectric constants of the upper and lower layers to invert the height of the free water layer, the upper layer's free water layer height is eliminated. The change in the dielectric constant of the oil-water mixture introduces errors in liquid level measurement, improving the accuracy of free water volume calculation. Third, by utilizing the position of the water level alarm line where the second dielectric constant sensing element is located, an alarm can be output in a timely manner when the free water level exceeds the alarm threshold, ensuring the safe operation of the equipment. Fourth, the entire detection process can be completed with only a single integrated detection probe and corresponding processing logic, resulting in a compact structure and low cost. It solves the comprehensive calculation problem of three forms of water (dissolved water, emulsified water, and free water) in oil, enabling online real-time detection and making it suitable for industrial site oil moisture monitoring scenarios. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0025] Figure 1 This is a schematic diagram of the structure of an oil moisture detection module in one embodiment; Figure 2 This is a schematic diagram of the structure of the first surface of the detection probe in one embodiment; Figure 3 This is a schematic diagram of the structure of the second surface of the detection probe in one embodiment; Figure 4 This is a flowchart illustrating a capacitive full-range oil moisture detection method in one embodiment. Figure 5 This is a flowchart illustrating the process of calculating the overall water content of the oil to be tested based on the first dielectric constant, the second dielectric constant, the overall capacitance value, and the total height corresponding to the preset liquid level in one embodiment. Figure 6 This is a schematic diagram of a process for calculating the overall water content based on the height of the free water layer and / or the height of the emulsified water layer, the second dielectric constant, and the total height in one embodiment. Figure 7 This is a schematic diagram of the dimensions and structure of the oil cavity in the oil moisture detection module in one embodiment; Figure 8This is a schematic diagram of the structure in one embodiment where the total capacitance value measured by the liquid level sensing element is broken down into a first sub-capacitance value and a second sub-capacitance value. Figure 9 This is a schematic diagram of the structure of an electronic device in one embodiment. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0027] All terms used in this application (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0028] For example, the terms "first," "second," etc., used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another.

[0029] For example, the terms "comprising" or "including" used in this application indicate the presence of features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0030] This application provides a capacitive full-range oil moisture detection method, which is applied in an oil moisture detection module. For example... Figures 1 to 3 As shown, the oil moisture detection module includes an oil chamber 110 and a detection probe 120 located in the oil chamber 110. The oil to be tested enters the oil chamber 110 through the oil passage 111 and the oil inlet 112, and can be discharged from the oil outlet 113. The detection probe 120 extends along the height direction of the oil chamber 110 and is used to detect the moisture-related parameters of the oil to be tested in the oil chamber 110.

[0031] In this embodiment, the detection probe 120 of the oil moisture detection module integrates multiple sensitive elements, specifically including a liquid level sensitive element 121, a first dielectric constant sensitive element 122, a second dielectric constant sensitive element 123, a temperature sensitive element 124, and a humidity sensitive element 125. These sensitive elements can all be integrated onto the signal transmission board 126 of the detection probe. The first dielectric constant sensitive element 122 is located in the bottom region of the detection probe 120 and is used to detect the dielectric constant of the oil near the bottom of the oil cavity 110. The second dielectric constant sensitive element 123 is located above the first dielectric constant sensitive element and is used to detect the dielectric constant of the upper region of the oil in the oil cavity 110. The dielectric constant sensitive elements are arranged vertically to avoid the problem that a single electrode cannot detect the dielectric constant drift at the bottom where there is high water content / free water.

[0032] Understandably, water in oil can be categorized into three types based on its content and form: dissolved water, emulsion water, and free water. Dissolved water refers to water dissolved in the oil at a molecular level; its content is usually low and influenced by the type of oil and temperature. For example, the dissolved water content of mineral oil at room temperature is generally in the tens to hundreds of ppm range. Emulsion water refers to water suspended in the oil as tiny droplets, forming a water-in-oil emulsion; its content increases with the oil's water content. Free water refers to free water that, due to its higher density than the oil, settles and accumulates at the bottom of the oil cavity under gravity. When free water stratifies in the oil, the aqueous phase deposits in the lower layer, and the oil-water mixture is in the upper layer. This results in a layered structure along the height of the medium in the oil cavity, with the water accumulating in the lower layer being free water, while the water in the upper layer typically exists as emulsion water.

[0033] In this embodiment, the dielectric constant is a physical quantity characterizing the polarization ability of a medium in an electric field. Medium with different dielectric constants has different effects on the output capacitance value of the capacitive sensor. Water and oil have significantly different dielectric constants. For example, the relative dielectric constant of water at room temperature is approximately 80, while that of mineral oil and other oils at room temperature is typically only 2 to 3. The equivalent dielectric constant of an oil-water mixture increases with its water content. Based on this principle, by measuring the dielectric constant of the medium region where the dielectric constant sensing element is located, the content and form of water in that region can be indirectly reflected.

[0034] In one embodiment, the specific structure of the detection probe 120 and the oil chamber 110 in the oil moisture detection module is further described. For example... Figures 1 to 3As shown, the first dielectric constant sensing element 122 is disposed at the bottom of the detection probe 120 and is used to detect the dielectric constant of the bottom region (i.e., the lower dielectric section) of the oil cavity 110; the second dielectric constant sensing element 123 is disposed in the detection probe 120 at the alarm height, i.e., above the first dielectric constant sensing element; the liquid level sensing element 121 is laid along the length of the detection probe 120 and covers the total height H0 of the oil to be tested, so as to measure the overall capacitance of the oil within the total height H0 range.

[0035] In this embodiment, the alarm height is the set height of the second dielectric constant sensing element on the detection probe 120, used to reflect whether the water content in the oil exceeds the critical value of the alarm amount. That is, the alarm height corresponds to the height of the free water layer when the water content in the oil reaches the preset alarm value.

[0036] Specifically, when the free water level in the oil chamber 110 rises to the position of the second dielectric constant sensing element (alarm height), the second dielectric constant sensing element will be immersed in the free water. The measured second dielectric constant will increase sharply from the value corresponding to the oil-water mixture (e.g., 5 to 15) to close to the dielectric constant of water (e.g., above 60), which is much greater than the dielectric constant of normal oil and oil-water mixtures. Therefore, by monitoring whether the second dielectric constant significantly exceeds the dielectric constant of the oil, it can be determined whether the free water level has exceeded the alarm height (water level alarm line), thereby triggering a water content alarm.

[0037] The alarm height setting can be determined based on the on-site water ingress and oil change indicators, such as the free water level height corresponding to the water ingress alarm moisture content specified by the equipment manufacturer. If there are no relevant on-site water ingress and oil change regulations, it can be set according to the conventional oil moisture control requirements. For example, the alarm height can be set at one-quarter to one-half of the total height of the oil chamber 110 to provide timely alarm before free water accumulates to a level that affects equipment operation. For instance, if the total height H0 is 200mm, and the on-site regulations stipulate that the free water level corresponding to the water ingress and oil change indicators should not exceed one-fifth of the height of the oil chamber 110, then the alarm height can be set at 40mm from the bottom. When the second dielectric constant sensing element measures that the second dielectric constant exceeds the second threshold, it indicates that the free water level has reached the 40mm alarm line, and the system outputs an alarm prompt.

[0038] Furthermore, the oil cavity 110 has an oil inlet 112 and an oil outlet 113, with the oil outlet 113 being higher than the oil inlet 112. The oil inlet 112 is located at a lower position in the oil cavity 110, and the oil to be tested enters the oil cavity 110 from bottom to top through the oil passage 111. The oil outlet 113 is located at a higher position in the oil cavity 110, and the tested oil flows back from the upper part of the oil cavity 110. The oil outlet 113 and the oil inlet 112 are respectively located on both sides of the oil cavity. By setting the oil outlet 113 higher than the oil inlet 112, it can be ensured that the oil fills the oil cavity 110 from bottom to top during the testing process and maintains upper backflow. This avoids disturbing the settled free water layer or causing free water to be discharged with the oil when the oil outlet 113 is located at the bottom, thereby maintaining the stability of the layered structure within the oil cavity.

[0039] In this embodiment, the detection probe 120 also integrates a temperature-sensitive element 124 and a humidity-sensitive element 125. The temperature-sensitive element 124 can be a thermistor or similar component, used to monitor the temperature of the oil in the oil chamber 110; the humidity-sensitive element 125 can be a humidity-sensitive film capacitor or similar component, used to monitor the water activity (dissolved water activity) of the oil. The humidity-sensitive element 125 is positioned no lower than the position of the second dielectric constant-sensitive element, that is, the humidity-sensitive element 125 is located in the upper region of the detection probe 120, to ensure that the humidity-sensitive element 125 is immersed in the upper layer of oil after oil stratification, thereby accurately measuring the water activity in the upper layer of oil.

[0040] For example, such as Figures 1 to 3 As shown, the detection probe 120 is provided with a first dielectric constant sensing element 122, a temperature sensing element 124, a second dielectric constant sensing element 123 and a humidity sensing element 125 from bottom to top, wherein the second dielectric constant sensing element 123 is located at the alarm height position.

[0041] Furthermore, the temperature-sensitive element 124, humidity-sensitive element 125, first dielectric constant-sensitive element 122, and second dielectric constant-sensitive element 123 are all disposed on the first side of the signal transmission plate 126 in the detection probe 120, and the liquid level-sensitive element 121 is disposed on the second side of the signal transmission plate 126, opposite to the first side. For example, the first side is the front of the signal transmission plate, and the second side is the back of the signal transmission plate. The detection probe is also provided with a water level warning line, which is lower than the water level alarm line. The temperature-sensitive element 124 can be disposed between the water level warning line and the water level alarm line, thereby enabling more accurate measurement of the oil temperature.

[0042] The signal transmission board 126 is used to carry the aforementioned sensitive elements and transmit the detection signals of each element. The electrical signals of each sensitive element are collected by the lines on the signal transmission board 126 and then transmitted to the detection circuit. The liquid level sensitive element 121 is placed on the second side of the signal transmission board 126 opposite to the first side. On the one hand, this makes the liquid level sensitive element 121 spatially offset from the temperature, humidity, and two dielectric constant sensitive elements, avoiding mutual interference between the electrode structures of each element. On the other hand, it can make full use of the circumferential space of the detection probe 120, so that the liquid level sensitive element 121 extends along the length of the detection probe 120 and covers the total height H0, ensuring the coverage of the liquid level measurement range without increasing the radial dimension of the probe.

[0043] For example, taking the detection probe 120 as a cylindrical probe extending along the axis of the oil cavity 110, the signal transmission board 126 can be arranged around the probe. The first side faces the inside of the oil cavity 110, and a humidity sensing element 125, a second dielectric constant sensing element 123, a temperature sensing element 124 and a first dielectric constant sensing element 122 are integrated sequentially from top to bottom along the height direction (length direction). The second side is opposite to the first side, and a planar electrode of a continuously extending liquid level sensing element 121 is laid on it along the length direction. The length of the liquid level sensing element 121 matches the total height H0 corresponding to the preset liquid level, so that the capacitance of the oil within the total height range is measured when the oil reaches the preset liquid level.

[0044] In this embodiment, by setting the second dielectric constant sensing element at the alarm height position, which serves as the water level alarm line, and utilizing the significant difference in dielectric constants between free water and oil, reliable monitoring and alarming of whether the free water level exceeds the limit are achieved. By setting the humidity sensing element at a position no lower than that of the second dielectric constant sensing element, it is ensured that the humidity sensing element is immersed in the upper layer of oil in a stratified state, providing conditions for measuring the water activity of the upper dissolved water. By integrating each sensing element onto two opposite sides of the signal transmission board, the compact integration of multiple sensing elements such as temperature, humidity, dual dielectric constants, and liquid level is achieved. This enables multi-parameter integrated in-situ detection within a small space (oil cavity), allowing a single detection probe to simultaneously collect all the original parameters required for full-range water content calculation, simplifying the structure of the detection module and reducing assembly and maintenance costs.

[0045] like Figure 4 As shown, the capacitive full-range oil moisture detection method in this embodiment includes the following steps S410 to S440. It should be noted that, in order to allow the oil in the oil chamber to settle and separate into layers, the oil can be allowed to settle in the oil chamber for a preset time before performing the relevant steps, so that the oil to be tested in the oil chamber is in a stable state.

[0046] Step S410: After the oil to be tested enters the oil cavity and reaches the preset liquid level in the oil cavity, the first dielectric constant of the lower medium of the oil to be tested is obtained through the first dielectric constant sensing element.

[0047] In this embodiment, the preset liquid level is the pre-defined detection liquid level of the oil to be tested in the oil chamber 110, that is, the standard liquid level height that the oil should reach in the oil chamber 110 when performing moisture detection. When the oil reaches the preset liquid level, the height of the oil in the oil chamber 110 is the total height corresponding to the preset liquid level, and this total height is subsequently recorded as H0. After the static stratification is completed, the oil covered by the total height H0 is divided into a lower medium segment and an upper medium segment from bottom to top. The lower medium segment may be a free water layer or an oil segment without free water, depending on the free water content in the oil.

[0048] The first dielectric constant sensing element 122 is a dielectric constant sensing element disposed at the bottom of the detection probe 120, and its detection area covers the medium near the bottom position within the oil cavity 110. Correspondingly, the first dielectric constant is the dielectric constant of the medium corresponding to the lower medium segment, measured by the first dielectric constant sensing element. The first dielectric constant sensing element is installed in the lower layer (near the bottom) of the oil cavity to detect the dielectric constant of the lower medium, primarily determining whether free water is present at the bottom.

[0049] When free water is present in the oil, since the density of free water is greater than that of oil, the free water settles to the bottom of the oil cavity 110 after standing. The first dielectric constant sensing element is immersed in the lower dielectric section. At this time, the first dielectric constant reflects the dielectric properties of the lower free water, and its value is significantly higher than that of the oil, for example, it can reach more than 60. When there is no free water in the oil, the first dielectric constant sensing element is immersed in the lower oil. At this time, the first dielectric constant is close to the dielectric constant of the oil itself.

[0050] A dielectric constant sensing element is essentially a capacitive sensor. Its working principle is based on the physical formula for a capacitor: capacitance C = ε1 × A1 / d1, where A1 is the area of ​​the plates and d1 is the distance between the plates. After measuring the dielectric constant, the corresponding capacitance can be calculated, or vice versa.

[0051] Specifically, the first dielectric constant sensing element can adopt any suitable capacitive sensor structure, such as a coaxial cylindrical capacitor structure, a parallel plate capacitor structure, or an interdigital capacitor structure. The first dielectric constant sensing element obtains the corresponding dielectric constant by detecting the capacitance value formed by the medium in its detection area.

[0052] For example, the first dielectric constant sensing element is a capacitive sensor with a coaxial cylindrical capacitor structure. Its inner electrode is a metal rod, and its outer electrode is a metal sleeve, both coaxially arranged. The dielectric material to be measured fills the annular gap between the inner and outer electrodes. The capacitance value C of this structure has a mapping relationship with the dimensions of its inner and outer electrodes and the effective length of the electrodes. Specifically, its capacitance value... Where a represents the inner electrode radius, b represents the outer electrode radius, and L represents the effective electrode length.

[0053] Taking a parallel-plate capacitor structure as an example, the first dielectric constant sensing element consists of two parallel electrode plates, with the dielectric material to be measured filling the space between the plates. Alternatively, an interdigital capacitor structure can be used as an example, consisting of two sets of staggered comb-shaped electrodes located in the same plane. Its working principle is based on the edge electric field effect; when the material to be measured is placed on the upper surface of the electrodes, the dielectric constant of the sensing region changes, and the inter-electrode capacitance changes linearly accordingly. The structure of this interdigital capacitor can be as shown in CN202411082236.4.

[0054] Since the height of the lower dielectric segment is directly related to the height of the free water layer, and the dielectric constant of the dielectric changes significantly with the water content state, the first dielectric constant can be used to distinguish whether the lower dielectric segment is in a state containing free water or not, and can be used as a quantitative characterization of the water content state of the lower dielectric segment.

[0055] For example, if a hydraulic oil is used as the test fluid, and the oil is left to stand in the oil chamber 110 for 30 minutes and reaches the preset level, if there is free water stratification in the oil, the measured first dielectric constant is about 78.5, which is close to the dielectric constant of water, indicating that the lower medium section is mainly free water; if the oil does not contain water or only contains a trace amount of dissolved water, for example, the measured first dielectric constant is about 2.2, which is close to the dielectric constant of the hydraulic oil itself, indicating that the lower medium section is oil.

[0056] Step S420: Obtain the second dielectric constant of the upper medium of the oil to be tested through the second dielectric constant sensing element.

[0057] The second dielectric constant sensing element 123 is positioned above the first dielectric constant sensing element (i.e., the upper region of the detection probe 120). Its detection area covers the upper medium of the oil to be tested within the oil cavity 110, i.e., the upper medium segment. The upper medium segment is the oil segment located above the lower medium segment. When free water stratification exists in the oil, the upper medium segment is the oil-water mixture located above the free water layer. The second dielectric constant is the dielectric constant of the medium corresponding to the upper medium segment, measured by the second dielectric constant sensing element. Its value increases with the increase of the water content in the upper medium segment (i.e., the water content of the upper oil-water mixture), and can be used to estimate the equivalent water content of the oil-water mixture in the upper medium segment.

[0058] In this embodiment, the second dielectric constant of the upper dielectric layer reflects the water content of the emulsion water layer in the upper dielectric layer. When free water stratifies in the oil, after the lower free water precipitates out, the water in the upper oil layer usually exists stably in the form of emulsion water. The higher the water content of the emulsion water in the upper dielectric layer, the greater the equivalent dielectric constant of the upper oil-water mixture. Therefore, the second dielectric constant can be used as a quantitative characterization of the water content of the upper dielectric layer. The mapping relationship between the second dielectric constant and the water content of the upper dielectric layer can be obtained through pre-calibration.

[0059] The second dielectric constant sensing element can also adopt any suitable capacitive sensor structure, such as a coaxial cylindrical capacitor structure, a parallel plate capacitor structure, or an interdigital capacitor structure. Its structure can be the same as or similar to that of the first dielectric constant sensing element, which will not be elaborated here.

[0060] For example, continuing the previous example, when there is free water stratification in the oil, the measured second dielectric constant is about 5.8, which is significantly higher than the dielectric constant of pure hydraulic oil (2.2), indicating that the water content of the emulsion water layer in the upper oil-water mixture has increased significantly; if there is no free water in the oil and no emulsification has occurred, the measured second dielectric constant is also close to the dielectric constant of the oil itself.

[0061] Step S430: Obtain the comprehensive capacitance value of the oil to be tested at the preset liquid level through the liquid level sensing element.

[0062] The level sensing element 121 is also a capacitive sensor, extending along the longitudinal direction of the detection probe (i.e., the height direction of the oil cavity), with an effective detection height not less than H0 (i.e., the total height corresponding to the preset liquid level). Specifically, it can be a planar electrode level detection element set on the detection probe 120, laid along the length direction of the detection probe 120, with its detection range covering the total height H0 corresponding to the preset liquid level. That is, the level sensing element 121 is simultaneously located within the height range of the oil cavity 110 occupied by the lower and upper media sections. Correspondingly, the comprehensive capacitance value is the capacitance value measured by the level sensing element 121 at the preset liquid level, which is formed by the superposition of the sub-capacitance values ​​contributed by the lower and upper media sections respectively. Since the detection area of ​​the level sensing element 121 simultaneously covers the upper and lower media sections, the measured comprehensive capacitance value C0 is related to the dielectric constant of the upper and lower media sections and the height of each media section. Therefore, the comprehensive capacitance value simultaneously contains information on the height of the free water layer and the water content information of the upper media section.

[0063] The capacitance value measured by a liquid level sensing element depends on the equivalent dielectric constant of the medium between its electrodes and the effective height of the medium covering the electrodes. For example... Figure 8As shown, when an upper dielectric segment (pure oil or emulsified water, dielectric constant ε2) and a lower dielectric segment (possibly free water, emulsified water, or pure oil, dielectric constant ε1) coexist within the oil cavity, the combined capacitance value C0 can be expressed as the sum of the first sub-capacitance value C1 contributed by the lower dielectric segment and the second sub-capacitance value C2 contributed by the upper dielectric segment, i.e., C0 = C1 + C2. The first sub-capacitance value C1 is related to the dielectric constant (first dielectric constant) and height of the lower dielectric segment, while the second sub-capacitance value C2 is related to the dielectric constant (second dielectric constant) and height of the upper dielectric segment. The quantitative relationship between the combined capacitance value C0, the first sub-capacitance value C1, and the second sub-capacitance value C2, and the method for inverting the height of each layer based on this relationship, are described in the embodiments below and will not be repeated here. If both the upper and lower layers are pure oil, then ε1≈ε2; if both the upper and lower layers are emulsified water, then ε1≈ε2; if the upper layer is emulsified water and the lower layer is free water, then ε1>ε2.

[0064] The first sub-capacitance value C1 = K × ε1 × H1, and the second sub-capacitance value C2 = K × ε2 × H2 = K × ε2 × (H0 - H1), where K is the probe structure coefficient of the liquid level sensing element. Therefore, the comprehensive capacitance value of the liquid level sensing element C0 = C1 + C2 = K × ε1 × H1 + K × ε2 × (H0 - H1). This formula reveals the quantitative relationship between the comprehensive capacitance value C0, the first dielectric constant ε1, the second dielectric constant ε2, and the free water layer height H1.

[0065] For example, continuing the previous example, suppose the total height H0 corresponding to the preset liquid level in the oil chamber 110 is 200mm. When the height of the free water layer is 30mm, the comprehensive capacitance value C0 measured by the liquid level sensing element 121 is about 3326pF (this value is related to the probe structure coefficient, and is converted according to the preset structure coefficient for ease of explanation).

[0066] Step S440: Calculate the overall water content of the oil to be tested based on the first dielectric constant, the second dielectric constant, the overall capacitance value, and the total height corresponding to the preset liquid level.

[0067] In this embodiment, the overall water content is the volume percentage of water contained in the oil to be tested, that is, the ratio of the volume occupied by all water in the oil cavity 110 (including lower free water, upper emulsified water, and dissolved water) to the total volume of oil in the oil cavity 110. Unlike existing technologies that can only detect a single form of water, this embodiment calculates the water content across all forms of water in the oil based on the total volume of the oil, thereby achieving full-range water content detection.

[0068] Specifically, the calculation logic for the overall water content is as follows: First, based on the first dielectric constant, the second dielectric constant, the overall capacitance value C0, and the total height H0 corresponding to the preset liquid level, the height of the free water layer in the lower medium section is determined; then, the equivalent water content of the emulsified water layer in the upper medium section is determined by combining the second dielectric constant; finally, the volume occupied by the free water in the lower layer and the equivalent water volume of the emulsified water in the upper layer are added together, and then divided by the total volume of the oil to obtain the overall water content of the oil to be tested.

[0069] It should be noted that when the oil contains dissolved water in addition to free water and emulsified water, or when the oil contains only dissolved water, the results of the detection by the temperature-sensitive element and the humidity-sensitive element can be combined for correction, or the dissolved water measurement scheme can be directly used to calculate the comprehensive water content. For the specific implementation method, please refer to the following embodiments.

[0070] In this embodiment, the dielectric constants of the lower and upper dielectric segments are obtained by the first and second dielectric constant sensing elements, respectively. Combined with the comprehensive capacitance value covering the total height obtained by the liquid level sensing element, the height information of the lower free water layer and the water content information of the upper dielectric segment can be captured simultaneously. Based on the total height corresponding to the preset liquid level, the comprehensive water content of the lower free water and the upper emulsion water is calculated. Compared to existing solutions that use only a single dielectric constant sensing element or a single liquid level capacitance for detection, this embodiment incorporates information on different forms of water under the layered structure into the calculation of the comprehensive water content. This not only identifies and quantifies the free water accumulated at the bottom of the oil cavity but also characterizes the emulsion water content in the upper oil-water mixture. It overcomes the problems of inaccurate detection due to free water stratification in high water content stages and the inability to detect beyond the measurement range, providing a foundation for full-range water content detection from trace dissolved water to high free water content.

[0071] In this embodiment, the specific implementation method of calculating the free water layer height of the lower dielectric segment based on the first dielectric constant, the second dielectric constant, the comprehensive capacitance value, and the total height in step S440 is further explained. For example... Figure 3 As shown, let the total height corresponding to the preset liquid level in the oil cavity 110 be H0, the height of the lower free water layer after settling and stratification be H1, and the height of the upper oil-water mixture (upper medium section) be H2, then H0 = H1 + H2. The liquid level sensing element 121 covers the area of ​​the oil cavity 110 corresponding to the total height H0, and its output comprehensive capacitance value C0 is contributed by both the lower and upper medium sections. The comprehensive capacitance value C0 satisfies the following superposition relationship: C0 = C1 + C2. C0 is the comprehensive capacitance value measured by the liquid level sensing element at the preset liquid level; C1 is the first sub-capacitance value contributed by the lower medium section; and C2 is the second sub-capacitance value contributed by the upper medium section.

[0072] In this embodiment, the first sub-capacitance value is the detection capacitance value of the portion of the liquid level sensing element located in the lower medium section (i.e., the height range occupied by the free water layer), and the second sub-capacitance value is the detection capacitance value of the portion of the liquid level sensing element located in the upper medium section (i.e., the height range occupied by the upper oil-water mixture). The lower medium section is immersed in the lower medium (free water or oil), and the upper medium section is immersed in the upper oil-water mixture. Therefore, the magnitude of the first sub-capacitance value depends on the dielectric constant of the lower medium and the height of the free water layer, and the magnitude of the second sub-capacitance value depends on the dielectric constant of the upper oil-water mixture and the height of the upper medium section. According to the parallel plate capacitance detection principle, the capacitance value of each segment is approximately proportional to the dielectric constant of that segment and the height of that segment along the probe length direction, that is: ; .

[0073] In the formula, K is the probe structure coefficient, which is determined by the structural parameters of the liquid level sensing element itself (such as electrode area, electrode spacing, shape factor, etc.) and can be obtained through calibration. It is the dielectric constant of the lower dielectric segment, i.e., the first dielectric constant; H0 is the dielectric constant of the upper dielectric layer, i.e., the second dielectric constant; H1 is the height of the lower free water layer; H2 is the height of the upper oil-water mixture, and the height of the upper oil-water mixture satisfies the relationship H0=H1+H2.

[0074] Based on this, we can obtain .

[0075] It should be noted that, due to the significant difference in dielectric constants between oil and water (e.g., the relative dielectric constant of pure oil is approximately 2 to 3, while that of water is approximately 80), the overall capacitance value C0 in this formula is highly sensitive to changes in the free water layer height H1. Based on this, it can be derived from the first dielectric constant... Second dielectric constant The combined capacitance value C0 and total height H0 uniquely determine the height H1 of the lower free water layer. Thus, without the need for separate float-type or electrode-pair-type level switches, the height of the free water layer can be accurately determined by combining the capacitance output of the same level-sensitive element with the dielectric constants of the upper and lower layers, thereby avoiding errors in level measurement caused by variations in the dielectric constant of the upper oil-water mixture.

[0076] For example, taking a certain hydraulic oil as an example, the total height H0 corresponding to the preset liquid level in the oil chamber 110 is 200mm. After settling and stratification, the first dielectric constant sensing element measures the first dielectric constant ε1 to be 78 (close to the dielectric constant of water, indicating that the lower medium section is free water), the second dielectric constant sensing element measures the second dielectric constant ε2 to be 5.8, and the liquid level sensing element measures the comprehensive capacitance value C0 to be 3326pF (assuming the probe structure coefficient K is calibrated to 1pF / mm). Substituting the above values ​​into the formula, the height of the free water layer H1 can be solved to be 30mm, that is, a free water layer with a height of 30mm has accumulated at the bottom of the oil chamber 110, and the height H2 of the upper oil-water mixture is 170mm.

[0077] In this embodiment, by establishing a quantitative relationship between the comprehensive capacitance value of the liquid level sensing element and the dielectric constant and layer height of the upper and lower layers, and by utilizing the significant difference in dielectric constant between the lower free water layer and the upper oil-water mixture, the height information of the lower free water layer is decoupled from the comprehensive capacitance value covering the total height. This not only reduces the interference of the change in dielectric constant of the upper oil-water mixture on the liquid level inversion results, but also provides a high-level basis for subsequent calculation of the free water volume in combination with the oil cavity size, and then for calculating the comprehensive water content across the entire range.

[0078] In one embodiment, after obtaining the free water layer height H1 of the lower medium section, the comprehensive water content of the oil to be tested can be calculated by combining the size data of the oil cavity and the equivalent water content of the upper medium section.

[0079] In this embodiment, based on the oil cavity size data, the free water layer height H1, and the total height H0, the total volume V0 of the oil to be tested, the volume V1 of the lower medium section (i.e., the volume of the lower free water layer), and the volume V2 of the upper medium section (i.e., the volume occupied by the upper oil-water mixture in the oil cavity) can be determined. Then, based on the equivalent water content of the upper medium section, the volume V3 of the emulsified water in the upper medium section can be determined. Therefore, the comprehensive water content α0 = (V3 + V1) / V0.

[0080] In this embodiment, based on the inverse free water layer height, the volume of the lower free water layer is calculated using the oil cavity size data, and the equivalent water content of the upper emulsion water layer is calculated using the equivalent water content of the emulsion water layer determined by the second dielectric constant. Finally, the two are normalized to a comprehensive water content based on the total oil volume. This method can accurately quantify the water content even in the high water content stage where free water stratification occurs in the oil, overcoming the limitations of the traditional capacitance method, which is affected by the distribution of water state during free water stratification and fails due to exceeding the measurement range at high water content. It achieves full-range measurement from low water content dissolved water and emulsion water states to high water content free water states.

[0081] In one embodiment, such as Figure 5 As shown, the calculation of the overall moisture content in step S440 can also be achieved in the following way: Step S510: The overall capacitance value is divided into a first sub-capacitance value contributed by the lower medium segment and a second sub-capacitance value contributed by the upper medium segment according to the total height corresponding to the preset liquid level.

[0082] Step S520: Based on the first mapping relationship between the first sub-capacitor value and the first dielectric constant, and the second mapping relationship between the second sub-capacitor value and the second dielectric constant, the height of the free water layer in the lower dielectric segment and / or the height of the emulsified water layer in the upper dielectric segment are inverted.

[0083] Step S530: Calculate the overall water content based on the height of the free water layer and / or the height of the emulsified water layer, the second dielectric constant, and the total height. The second dielectric constant reflects the equivalent water content of the emulsified water layer in the upper medium of the oil to be tested.

[0084] In this embodiment, the first sub-capacitor value C1 reflects the capacitance contribution within the height range of the lower dielectric segment, and the second sub-capacitor value C2 reflects the capacitance contribution within the height range of the upper dielectric segment. The values ​​of C1 and C2 need to be obtained based on the height of each dielectric segment, and are not directly acquired.

[0085] The first mapping relationship is the correspondence between the first sub-capacitor value and the first dielectric constant. It is used to describe the relationship between the capacitance contributed by the lower dielectric segment and the dielectric constant and layer height of the lower dielectric. For example, it can be constructed based on the parallel plate capacitance detection principle, C1=K×ε1×H1; The second mapping relationship is the correspondence between the second sub-capacitor value and the second dielectric constant. It is used to describe the relationship between the capacitance contributed by the upper dielectric segment and the dielectric constant and layer height of the upper dielectric, C2=K×ε2×H2.

[0086] During testing, since the first and second dielectric constants have already been measured by the first and second dielectric constant sensing elements, respectively, after obtaining the relationship between the first sub-capacitance value, the second sub-capacitance value, and the layer height of the corresponding dielectric segment, the results are based on the directly measured values ​​of C0, ε1, ε2, etc., and are processed according to... The height H1 of the free water layer in the lower medium segment and / or the height H2 (H0-H1) of the emulsified water layer (oil-water mixture layer) in the upper medium segment can be derived separately, thereby decoupling the capacitance information into the height information of each layer.

[0087] After reversing the height H1 of the lower free water layer and / or the height H2 of the upper medium section, the equivalent water content of the emulsion water layer of the upper medium section can be determined by combining the second dielectric constant. Then, the free water volume, emulsion water volume and overall water content can be calculated in the manner shown in the above embodiment.

[0088] Specifically, such as Figure 6As shown, the comprehensive water cut is calculated based on the height of the free water layer and / or the height of the emulsified water layer, the second dielectric constant, and the total height, including: Step S610: Calculate the volume of free water based on the height of the free water layer and the size of the oil cavity.

[0089] Step S620: Determine the equivalent water content of the emulsion water in the upper medium of the oil to be tested based on the second dielectric constant, and determine the volume of the emulsion water in combination with the space volume occupied by the upper medium of the oil to be tested in the oil cavity.

[0090] Step S630: The volume of free water and the volume of emulsified water are added together, and the overall water content is calculated based on the total volume of oil in the oil cavity.

[0091] In this embodiment, taking a cylindrical oil cavity as an example, the dimensions of the oil cavity include the radial dimension of the oil cavity 110. Combined with... Figure 7 As shown, for example, when the oil cavity is a cylindrical cavity, the diameter is 2R and the radius is R. Since the cross-sectional area of ​​the oil cavity can be determined by its radial dimension, based on the known free water layer height H1 and total height H0, the volume occupied by the lower free water layer and the total volume of oil in the oil cavity 110 can be calculated using the radius R. The volume of the lower free water layer is... Total volume of oil In the formula, V0 is the total volume of oil in oil cavity 110; R is the radius of oil cavity; H1 is the height of the lower free water layer (free water layer height). The volume occupied by the upper oil-water mixture in the oil cavity is V2 = V0 - V1.

[0092] For the upper medium layer, its water content is characterized by the equivalent water content. Specifically, when free water stratifies in the oil, the water in the upper oil layer is in a supersaturated state and exists stably in the upper oil-water mixture in the form of emulsion water. In this embodiment, the water content of the emulsion water layer in the upper medium layer is recorded as the equivalent water content. Equivalent moisture content The equivalent water content of the upper medium section can be determined by measuring the second dielectric constant through a second dielectric constant sensing element. This involves establishing a mapping relationship between the second dielectric constant and the water content of the emulsion layer beforehand through offline calibration. During detection, the measured second dielectric constant is substituted into this mapping relationship to obtain the equivalent water content of the current upper medium section. The volume of emulsified water in the upper oil-water mixture (i.e., the volume of emulsified water) is V3 = V2 × α1.

[0093] Using the total oil volume V0 as a baseline, the volume of all water in the oil cavity is normalized. When the cross-sectional area of ​​the oil cavity 110 is consistent along the height direction, the comprehensive water content of the oil to be tested is obtained. :

[0094] Understandably, the oil cavity can be any other suitable shape besides a cylindrical cavity. Based on the corresponding size data of the oil cavity, the overall moisture content can still be calculated.

[0095] In this embodiment, the overall capacitance value covering the total height is first divided into sub-capacitance values ​​for the upper and lower dielectric segments according to height. Then, the height of each layer is inverted through the mapping relationship between the sub-capacitance values ​​and the dielectric constant. Finally, the overall moisture content is calculated by summing the radial dimensions of the oil cavity and the equivalent water content of the upper emulsion water layer on the overall volume basis. Since the capacitance of each segment is only related to that segment of the dielectric, the split inversion method can further suppress the influence of interlayer coupling on the accuracy of height inversion, providing a parallel implementation scheme for the accurate measurement of overall moisture content under high water content conditions.

[0096] In one embodiment, before obtaining the first dielectric constant of the lower medium of the oil to be tested through the first dielectric constant sensing element, the method may further include: letting the oil to be tested stand in the oil cavity for a preset time to allow the oil to be tested to be fully separated in the oil cavity before performing steps S410 to S440.

[0097] In this embodiment, the preset settling time refers to the duration during which the oil to be tested remains stationary after entering the oil chamber and reaching the preset liquid level. The specific value of the preset time can be determined according to the type, viscosity, temperature, and operating conditions of the oil circuit, for example, it can be set to 5 minutes, 10 minutes, 20 minutes, or 30 minutes. Generally speaking, the higher the viscosity of the oil and the lower the ambient temperature, the slower the rate of water sedimentation and stratification, and the longer the required settling time. For high-viscosity oils or low-temperature operating conditions, the preset time can be set to a longer value, such as 30 minutes, to ensure that the lower free water can settle sufficiently and that a stable stratification interface is formed between the upper and lower media.

[0098] Specifically, when the oil to be tested enters the oil chamber during the pumping process, water and oil are often in a mixed state. If the measurement is performed directly without allowing it to settle, the water distribution in the areas where the first and second dielectric constant sensing elements are located is unstable. The measured first dielectric constant, second dielectric constant, and overall capacitance values ​​cannot accurately reflect the steady-state dielectric properties of each medium layer, thus affecting the accuracy of free water layer height inversion and overall water content calculation. By allowing the oil to be tested to settle in the oil chamber for a preset time, allowing the free water to fully settle and form the lower medium layer, and the oil-water mixture to stabilize in the upper medium layer, measurement can be performed. This ensures that the first dielectric constant reflects the true dielectric properties of the lower medium layer, and the second dielectric constant reflects the true dielectric properties of the upper oil-water mixture, thus providing a stable measurement basis for accurate calculation of the full-range water content.

[0099] For example, using gear oil with high viscosity at low temperatures as the test oil, after the test oil enters the oil chamber and reaches the preset liquid level, it is left to stand for 30 minutes to allow any water that may be carried in the gear oil to settle completely. After standing, if there is free water at the bottom of the oil chamber, a stable free water layer is formed. At this time, steps S410 to S440 are executed, and the measured first dielectric constant, second dielectric constant, and comprehensive capacitance value are the values ​​under the stable layered state.

[0100] In this embodiment, by allowing the oil to stand for a preset time before testing, the oil is ensured to be fully settled and layered in the oil cavity. This overcomes the defect that the dielectric constant and capacitance measurement results fluctuate with flow field disturbance under oil-water mixed state. It provides stable and repeatable measurement conditions for dielectric constant measurement and free water layer height inversion based on layered structure, and further improves the accuracy and consistency of comprehensive water content measurement.

[0101] In one embodiment, before performing step S440 to calculate the overall water content based on the first dielectric constant, the second dielectric constant, the comprehensive capacitance value, and the total height, the method may further include: determining, based on the first dielectric constant and / or the second dielectric constant, whether the water in the upper medium of the oil to be tested is emulsified water and whether the water in the lower medium of the oil to be tested is free water; if the water in the upper medium is emulsified water and the water in the lower medium is free water, then step S440 is performed to calculate the overall water content; otherwise, the corresponding measurement scheme can be selected to calculate the overall water content according to other water forms of the upper and lower media (such as both being dissolved water, both being emulsified water, both being free water, etc.).

[0102] In this embodiment, emulsified water refers to water in the oil that exists in an emulsified or supersaturated form after reaching its solubility limit. The dielectric constant of this medium is significantly higher than that of pure oil but lower than that of free water. Free water refers to free water that settles and accumulates at the bottom of the oil cavity; the dielectric constant of this medium is close to that of water. Since the dielectric constants of the upper and lower media exhibit distinctly separable ranges depending on their water content, the water content in the upper and lower media can be determined based on the comparison between the first and / or second dielectric constants and a preset threshold.

[0103] Specifically, this embodiment sets four dielectric constant discrimination thresholds: a first threshold, a second threshold, a third threshold, and a fourth threshold. The value of each threshold is related to the type of oil being tested and the calibration results. For example, the third threshold can be set to < the fourth threshold < the second threshold. The first threshold is used to characterize the significance of the difference in dielectric constant between the upper and lower layers. For example, for a certain hydraulic oil, the third threshold can be set to 3, the fourth threshold to 20, the second threshold to 45, and the first threshold to 15. Based on the above thresholds, the determination of the moisture form in the upper and lower media includes any one of the following situations.

[0104] Scenario 1: When the first dielectric constant exceeds the second threshold and the second dielectric constant is less than the second threshold, the water in the upper medium of the tested oil is determined to be emulsified water, and the water in the lower medium of the tested oil is determined to be free water. In this scenario, the lower medium has a higher dielectric constant (exceeding the second threshold), indicating that the lower medium segment is free water; the upper medium has a dielectric constant that does not exceed the second threshold, indicating that the upper medium segment has not been submerged by free water, and the water in the upper oil-water mixture exists in the form of emulsified water. Continuing the previous example, when the first dielectric constant is 78 and the second dielectric constant is 5.8, the first dielectric constant exceeds the second threshold of 45, and the second dielectric constant of 5.8 is less than the second threshold of 45, which falls under this scenario. It can be determined that the lower medium segment is free water and the upper medium segment is an oil-water mixture containing emulsified water, and then step S440 is executed to calculate the comprehensive water content according to the corresponding scheme.

[0105] Scenario 2: When the difference between the first and second dielectric constants exceeds the first threshold, the water in the upper medium of the tested oil is determined to be emulsified water, and the water in the lower medium is determined to be free water. This scenario utilizes the significant difference in dielectric constant between the lower free water and the upper oil-water mixture for determination. When the difference exceeds the first threshold, it indicates that the dielectric constant of the lower medium is significantly higher than that of the upper medium, meaning that free water has accumulated in the lower layer and the upper layer is an oil-water mixture. For example, when the first dielectric constant is 78 and the second dielectric constant is 5.8, the difference of 72.2 exceeds the first threshold of 15, thus determining that the upper layer is emulsified water and the lower layer is free water. Scenario 1 and Scenario 2 can be used alone or in combination. When the results of both determinations are consistent, the reliability of the determination can be further improved.

[0106] Scenario 3: When the first dielectric constant and / or the second dielectric constant are less than the third threshold, both the upper and lower media of the tested oil are determined to be dissolved water. In this scenario, the dielectric constants of both media are close to those of pure oil (below the third threshold), indicating that no emulsified water or free water has formed in the oil, and the water is dissolved in the oil only in a molecular state, belonging to a trace amount of dissolved water. In this case, the overall water content can be directly calculated based on the humidity-sensitive element and the thermodynamic equilibrium model.

[0107] Scenario 4: When the first dielectric constant and / or the second dielectric constant are greater than the third threshold and less than the fourth threshold, both the upper and lower media of the tested oil are determined to be emulsified water. In this scenario, the dielectric constants of the two media are in the middle range between the third and fourth thresholds, higher than the level of pure oil but lower than the level of free water, indicating that the water in the oil has reached saturation and is uniformly dispersed in the upper and lower oil layers in the form of emulsified water, without any free water settling or precipitating out. In this case, the overall water content can be directly calculated based on the mapping relationship between the second dielectric constant and the water content of the emulsified water layer.

[0108] Scenario 5: When the second dielectric constant exceeds the second threshold, it is determined that the water in both the upper and lower media of the tested oil is free water. In this scenario, the second dielectric constant measured by the upper dielectric constant sensing element has exceeded the second threshold, indicating that the free water level has risen to the point of submerging the upper element. That is, both the upper and lower media in the oil chamber are occupied by free water, the water content of the oil is extremely high, the water content has exceeded the alarm threshold, and an alarm is output.

[0109] In this embodiment, before calculating the overall moisture content, the form of water in the upper and lower media is first determined based on the first and second dielectric constants. A measurement scheme matching the water form is then selected accordingly, avoiding incorrect results caused by misusing this calculation method when the water form is not suitable for volume-based overall moisture content calculation (such as pure dissolved water or unstratified emulsion). Simultaneously, through the combination of multiple thresholds and various scenarios, the system can adaptively identify different water forms and content stages in the oil, from trace dissolved water and emulsion to free water stratification and even complete free water, providing an accurate basis for subsequent moisture content calculations corresponding to each form.

[0110] In one embodiment, when the water content in both the upper and lower media of the oil to be tested is emulsified water (i.e., the first dielectric constant and / or the second dielectric constant is greater than the third threshold and less than the fourth threshold), the overall water content can be determined based on the mapping relationship between the second dielectric constant and the water content of the emulsified water layer.

[0111] In this embodiment, when both the upper and lower media are emulsified water, the water in the oil is uniformly dispersed in the oil in the form of emulsified water, and free water has not yet settled and precipitated out. The water content of the upper and lower media in the oil cavity is basically the same. At this time, the water content of the upper media section represents the water content of the oil in the entire oil cavity. Therefore, it is only necessary to measure the second dielectric constant through the second dielectric constant sensing element, and then convert the second dielectric constant into the equivalent water content of the emulsified water layer according to the pre-calibrated mapping relationship between the second dielectric constant and the water content of the emulsified water layer. This water content can then be used as the comprehensive water content of the oil to be tested.

[0112] Specifically, the mapping relationship between the second dielectric constant and the water content of the emulsion water layer can be pre-calibrated as follows: Prepare a series of oil-water emulsion standard samples with known water contents (e.g., water contents of 1%, 2%, 5%, 8%, 10%, 15%, 20%, etc.), introduce each standard sample into the oil cavity, immerse the second dielectric constant sensing element in each standard sample, and measure the second dielectric constant corresponding to each water content to obtain a dielectric constant-water content data point set; then fit this data point set to construct the mapping relationship between the second dielectric constant and the water content of the emulsion water layer. For example, linear fitting, polynomial fitting, or piecewise interpolation can be used to establish the mapping relationship, or the data point set can be made into a mapping lookup table and stored in the detection module. Since the higher the water content of the oil and the greater the emulsion water content, the higher the equivalent dielectric constant of the oil, this mapping relationship is monotonically increasing. Therefore, the equivalent water content of the emulsion water layer can be uniquely determined by the measured second dielectric constant.

[0113] For example, taking a certain hydraulic oil as an example, the calibration yields the following correspondence between the second dielectric constant and the water content of the emulsion layer: a second dielectric constant of 3.6 results in a water content of 2%, 5.0 in 5.0, 8% in 5.8, 10% in 6.9, and 15% in 9.5. During testing, if both the upper and lower layers are determined to be emulsion water, and the measured second dielectric constant is 6.2, then according to the above mapping relationship, the water content of the emulsion layer can be interpolated to determine that it is approximately 8.7%. This value is then used as the overall water content output of the oil being tested.

[0114] In this embodiment, when the water content of the oil rises to the state of emulsified water but before the free water has separated into layers, the comprehensive water content is determined directly based on the calibration mapping relationship between the second dielectric constant and the water content of the emulsified water layer. This fully utilizes the characteristics of the dielectric constant being sensitive to the emulsified water content and having a stable calibration relationship, providing a simple and reliable measurement method for this water form. It is interconnected with the dissolved water scheme and the free water scheme to jointly constitute the complete scheme for full-range water content detection in this application.

[0115] In one embodiment, when the water in both the upper and lower media of the oil is dissolved water (the first dielectric constant and / or the second dielectric constant is less than the third threshold), the method further includes the step of measuring the overall water content under the dissolved water state: obtaining the water activity value measured by the humidity-sensitive element; obtaining the temperature value measured by the temperature-sensitive element; and inputting the water activity value and the temperature value into a preset water calculation model based on the principle of solution thermodynamic equilibrium to calculate the overall water content.

[0116] In this embodiment, water activity is a measure of the chemical potential of dissolved water in the oil, reflecting the activity of water in the oil relative to the saturated vapor pressure of pure water. For oil, the saturated solubility of water in the oil at a certain temperature is a fixed value. When the amount of dissolved water in the oil increases, the water activity increases accordingly, and the dielectric constant of the oil also increases. In the dissolved water state, the water in the oil is uniformly dissolved in the oil in a molecular state, without forming emulsion droplets or free water phase. Therefore, it is impossible to accurately characterize its water content through conventional methods such as emulsion water dielectric constant mapping or free water volume measurement. However, there is a deterministic relationship between water activity and water content under thermodynamic equilibrium conditions. Therefore, the content of dissolved water can be calculated by combining water activity with temperature. The water calculation model based on the principle of solution thermodynamic equilibrium utilizes this relationship, and its specific form can be expressed as a functional relationship between the volume of dissolved water V4, the water activity aw, and the temperature T: Then, based on the overall moisture content... The overall moisture content can be calculated.

[0117] In the formula, aw is the water activity value measured by the humidity-sensitive element; T is the temperature value measured by the temperature-sensitive element; A and B are solubility coefficients, which are related to the type of oil and can be obtained by calibrating the solubility coefficients for different oils. The temperature term in the moisture calculation model corrects for the effect of temperature on the saturated solubility of water in the oil: as the temperature increases, the saturated solubility of the oil increases, and more water can dissolve under the same water activity. Therefore, the model compensates for the water content through the temperature term. It should be noted that the water activity value can be obtained offline by calibrating the humidity-sensitive element, establishing a definite correspondence between the output of the humidity-sensitive element and the water activity value.

[0118] For example, taking a certain turbine oil as an example, the solubility coefficients A and B of the oil are pre-calibrated. During testing, if it is determined that both the upper and lower media are in a dissolved water state, and the water activity aw is measured to be 0.6 and the temperature T is 40℃, these values ​​are input into the moisture calculation model to calculate the water content corresponding to the dissolved water in the current oil, thereby determining the overall moisture content. Since the upper and lower media in the oil cavity are homogeneous oil in the dissolved water state, and there is no stratification difference, the water content calculated by the model is the water content of the entire oil cavity, which can be directly used as the overall moisture content output.

[0119] In this embodiment, for the state of trace dissolved water, the activity of water is measured by a humidity-sensitive element and the temperature value is measured by a temperature-sensitive element. The dissolved water content is calculated by a water content calculation model based on the principle of solution thermodynamic equilibrium. This makes up for the lack of sensitivity of dielectric constant measurement in the trace water range, so that the trace water inlet stage of oil before emulsification and stratification can be accurately quantified. Thus, the measurement of the starting point of the full range of water content coverage from trace dissolved water to high free water content is realized.

[0120] In this embodiment, the oil moisture detection module integrates a liquid level sensing element, a first dielectric constant sensing element, a second dielectric constant sensing element, a temperature sensing element, and a humidity sensing element on a single detection probe. Through segmented detection and unified calculation of different forms of moisture after static stratification, it achieves full-range comprehensive moisture content measurement of dissolved water, emulsified water, and free water in the oil. Specifically: for trace amounts of dissolved water, the water activity is measured using a humidity sensing element and quantified using a temperature sensing element and a thermodynamic equilibrium model; for emulsified water, the moisture content of the upper medium segment is determined by the second dielectric constant measured by the second dielectric constant sensing element and its calibration mapping relationship; for stratified free water, the height of the free water layer is inverted by combining the comprehensive capacitance value measured by the liquid level sensing element with the dielectric constants of the upper and lower layers, and then the free water volume is calculated by combining the oil cavity size data, and then unified and normalized with the converted volume of the upper emulsified water to obtain the comprehensive moisture content.

[0121] Compared with the prior art, the embodiments of this application have the following beneficial effects: First, by measuring different forms of moisture separately after static stratification and then uniformly converting them, the coupling interference of moisture form distribution on capacitance measurement results is avoided, so that the moisture content in the high water content stage (when free water stratification occurs) can still be accurately measured, breaking through the limitations of traditional capacitance method in that the measurement error is large when free water stratification occurs and it fails when the detection range is exceeded in high water content; Second, by covering the total height of the liquid level sensitive element and combining the dielectric constant of the upper and lower layers to invert the height of the free water layer, the dielectric constant of the upper oil-water mixture is eliminated. The constant change introduces errors in liquid level measurement, improving the accuracy of free water volume calculation; third, by utilizing the position of the water level alarm line where the second dielectric constant sensing element is located, an alarm can be output in a timely manner when the free water level exceeds the alarm threshold, ensuring the safe operation of the equipment; fourth, the entire detection process can be completed with only a single integrated detection probe and corresponding processing logic, resulting in a compact structure, low cost, and the ability to achieve online real-time detection. It solves the comprehensive calculation problem of three forms of water (dissolved water, emulsified water, and free water) in oil, making it suitable for industrial site oil moisture monitoring scenarios.

[0122] It is understood that the shape of the oil cavity, the preset liquid level, the preset duration, the thresholds (first threshold, second threshold, third threshold, and fourth threshold), and the numerical examples described in the above embodiments are all illustrative. Those skilled in the art can adjust them according to the actual oil type, oil cavity size, and operating conditions, and the specific values ​​do not constitute a limitation on the scope of protection of this application. The technical features described in the above embodiments can be arbitrarily combined and used without conflict. For example, the determination results of each water form can be used as the trigger condition for the corresponding measurement scheme, and can also be used to cross-verify the measurement results of other embodiments. These will not be elaborated further here.

[0123] In one embodiment, a computer-readable storage medium is provided having executable instructions stored thereon, which, when executed by a processor, cause the processor to perform the steps in the above method embodiments.

[0124] In one embodiment, an electronic device is also provided, including one or more processors; and a memory storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors perform the steps in the above method embodiments.

[0125] In one embodiment, such as Figure 9 The diagram illustrates the structure of an electronic device used to implement an embodiment of this application. The electronic device includes a CPU 701, which can perform various appropriate actions and processes according to a program in ROM 702 or a program loaded from storage portion 708 into RAM 703. RAM 703 also stores various programs and data required for the operation of the electronic device. The CPU 701, ROM 702, and RAM 703 are interconnected via a bus 704. An I / O interface 705 is also connected to the bus 704.

[0126] The following components are connected to the I / O interface 705: an input section 706 including a keyboard, mouse, etc.; an output section 707 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and speakers, etc.; a storage section 708 including a hard disk, etc.; and a communication section 709 including a network interface card such as a LAN card, modem, etc. The communication section 709 performs communication processing via a network such as the Internet. A drive 710 is also connected to the I / O interface 705 as needed. A removable medium 711, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on the drive 710 as needed so that computer programs read from it can be installed into the storage section 708 as needed.

[0127] Specifically, according to embodiments of this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this application include a computer program product comprising a computer-readable medium carrying instructions that, in such embodiments, can be downloaded and installed from a network via communication section 709, and / or installed from removable medium 711. When the instructions are executed by CPU 701, the various method steps described in this application are performed.

[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0129] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are meant to be within the scope of this application and form different embodiments. For example, all the embodiments above can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A capacitance-based full-range oil moisture detection method, characterized in that, The method is applied in an oil moisture detection module, which includes an oil chamber and a detection probe located within the oil chamber. The detection probe integrates a liquid level sensing element, a first dielectric constant sensing element, and a second dielectric constant sensing element located above the first dielectric constant sensing element. The method includes: After the oil to be tested enters the oil cavity and reaches the preset liquid level in the oil cavity, the first dielectric constant of the lower medium of the oil to be tested is obtained by the first dielectric constant sensing element. The second dielectric constant of the upper medium of the oil under test is obtained by the second dielectric constant sensing element; The comprehensive capacitance value of the oil under test at the preset liquid level is obtained through the liquid level sensing element; The overall capacitance value is divided into a first sub-capacitance value contributed by the lower medium segment and a second sub-capacitance value contributed by the upper medium segment according to the total height corresponding to the preset liquid level. Based on the first mapping relationship between the first sub-capacitor value and the first dielectric constant, and the second mapping relationship between the second sub-capacitor value and the second dielectric constant, the height of the free water layer in the lower dielectric segment and / or the height of the emulsified water layer in the upper dielectric segment can be deduced. The overall water cut is calculated based on the height of the free water layer and / or the height of the emulsified water layer, the second dielectric constant, and the total height. The second dielectric constant reflects the equivalent water cut of the emulsified water layer of the upper medium of the oil to be tested.

2. The method according to claim 1, characterized in that, The calculation of the overall water cut based on the height of the free water layer and / or the height of the emulsified water layer, the second dielectric constant, and the total height includes: The volume of free water is calculated based on the height of the free water layer and the dimensions of the oil cavity; The equivalent water content of the emulsion water in the upper medium of the oil to be tested is determined based on the second dielectric constant, and the volume of emulsion water is determined by combining the space volume occupied by the upper medium of the oil to be tested in the oil cavity. The free water volume and the emulsified water volume are added together, and the overall water content is calculated based on the total oil volume in the oil cavity.

3. The method according to claim 1, characterized in that, Before obtaining the first dielectric constant of the lower medium of the oil under test through the first dielectric constant sensing element, the method further includes: The oil to be tested is left to stand in the oil chamber for a preset time; Before dividing the overall capacitance value into a first sub-capacitance value contributed by the lower medium segment and a second sub-capacitance value contributed by the upper medium segment according to the total height corresponding to the preset liquid level, the method further includes: Based on the first dielectric constant and / or the second dielectric constant, determine whether the water in the upper medium of the oil to be tested is emulsified water, and whether the water in the lower medium of the oil to be tested is free water. If so, then execute the step of splitting the comprehensive capacitance value into a first sub-capacitance value contributed by the lower medium segment and a second sub-capacitance value contributed by the upper medium segment according to the total height corresponding to the preset liquid level.

4. The method according to claim 3, characterized in that, The step of determining whether the water in the upper medium of the oil to be tested is emulsified water and whether the water in the lower medium of the oil to be tested is free water based on the first dielectric constant and / or the second dielectric constant includes: When the first dielectric constant exceeds the second threshold and the second dielectric constant is less than the second threshold, it is determined that the water in the upper medium of the oil to be tested is emulsified water and the water in the lower medium of the oil to be tested is free water. Alternatively, when the difference between the first dielectric constant and the second dielectric constant exceeds the first threshold, it is determined that the water in the upper medium of the oil to be tested is emulsified water, and the water in the lower medium of the oil to be tested is free water. Alternatively, if the first dielectric constant and / or the second dielectric constant are less than the third threshold, it is determined that both the upper medium of the oil to be tested and the lower medium of the oil to be tested are dissolved water. Alternatively, if the first dielectric constant and / or the second dielectric constant are greater than the third threshold and less than the fourth threshold, it is determined that both the upper medium of the oil to be tested and the lower medium of the oil to be tested are emulsified water. Alternatively, when the second dielectric constant exceeds the second threshold, it is determined that the water in both the upper and lower layers of the oil being tested is free water.

5. The method according to claim 4, characterized in that, When both the upper and lower media of the oil to be tested are emulsified water, the overall water content is determined based on the mapping relationship between the second dielectric constant and the equivalent water content of the emulsified water layer.

6. The method according to any one of claims 1 to 5, characterized in that, The first dielectric constant sensing element is disposed at the bottom of the detection probe, and the second dielectric constant sensing element is disposed in the detection probe at an alarm height, which corresponds to the height of the free water layer when the water content in the oil reaches a preset alarm value. The liquid level sensing element is laid along the length of the detection probe, and the liquid level sensing element covers the total height of the oil to be tested.

7. The method according to claim 6, characterized in that, The oil cavity has an oil inlet and an oil outlet, and the oil outlet is higher than the oil inlet. The detection probe also integrates a temperature-sensitive element and a humidity-sensitive element, and the position of the humidity-sensitive element is not lower than the position of the second dielectric constant-sensitive element; The temperature-sensitive element, humidity-sensitive element, first dielectric constant-sensitive element, and second dielectric constant-sensitive element are located on the first side of the signal transmission plate of the detection probe, and the liquid level-sensitive element is located on the second side of the signal transmission plate, with the second side opposite to the first side.

8. The method according to claim 7, characterized in that, The method further includes: When the first dielectric constant and / or the second dielectric constant are less than the third threshold, it is determined that both the upper medium and the lower medium of the oil to be tested are dissolved water. Obtain the water activity value measured by the humidity-sensitive element; Obtain the temperature value measured by the temperature-sensitive element; The water activity value and the temperature value are input into a preset water calculation model based on the principle of solution thermodynamic equilibrium to calculate the overall water content.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores executable instructions that, when executed by a processor, cause the processor to perform the method as described in any one of claims 1 to 8.

10. An electronic device, characterized in that, include: One or more processors; A memory for storing one or more programs, which, when executed by one or more processors, cause the one or more processors to perform the method as described in any one of claims 1 to 8.

Images