A liquid foam height measuring apparatus

Abstract

The application discloses a liquid foam height measuring device and relates to the technical field of liquid measurement. The device comprises a container, a high-sensitivity capacitive sensor, a low-sensitivity capacitive sensor, a hardware measuring circuit and a connecting wire harness. The high-sensitivity capacitive sensor is highly sensitive to the dielectric constant of a liquid, and the low-sensitivity capacitive sensor is not sensitive to the dielectric constant of the liquid. The hardware measuring circuit collects the capacitance data of the two sensors, and the liquid height and the liquid foam height are calculated through the linear equations of the two capacitive sensors. The application can measure the height of liquid foam in real time and feed back accurate height values, solves the problem that the existing sensor can only detect whether there is foam but cannot measure the foam height in real time, and is also applicable to the height measurement of any two kinds of liquids with different dielectric constants.

Description

Technical Field

[0001] This invention relates to the field of liquid measurement technology, specifically to a measuring device capable of measuring the real-time height of two liquid media. Background Technology

[0002] In many fields, liquid foam is an indispensable carrier for achieving specific functions, possessing irreplaceable engineering and practical value. However, in many production processes, uncontrolled foam growth can significantly reduce production efficiency, damage product quality, shorten equipment lifespan, and even cause safety issues and environmental risks. Due to the dual nature of liquid foam, real-time measurement and intelligent control have become an urgent need for modern industrial intelligent upgrading and high-quality production. This makes the development of liquid foam sensors capable of real-time measurement both practically necessary and of significant academic value.

[0003] There are many types of liquid sensors on the market, including capacitive sensors, optical sensors, and acoustic sensors, but there are basically no instruments that directly measure the height of liquid foam. Most foam sensors either remove foam as an interference factor or simply use the sensor to measure the presence or absence of foam, functioning as an alarm switch—that is, when the foam reaches a certain height, the switch is triggered. These sensors often only measure the presence or absence of foam, and cannot accurately measure the height of the foam.

[0004] For example, a common non-contact capacitive sensor is fixed in a certain position. When the foam height reaches a certain level, the difference between the air and the foam medium changes the capacitance value of the sensor, thus triggering an alarm. This type of sensor can only act as a switch to detect the presence of liquid foam, and cannot measure the height of the liquid foam in real time. Therefore, a liquid foam height measuring device is proposed to address the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a measuring device capable of measuring the height of liquid foam in real time, thereby solving the problem of the inability to quantitatively detect the height of liquid foam in real time in the prior art by continuously outputting accurate height values.

[0006] To achieve the above objectives, the present invention provides a liquid foam height measuring device, including a container, a high-sensitivity capacitive sensor, a low-sensitivity capacitive sensor, a hardware measuring circuit, and a connecting harness.

[0007] The container can be made of various materials that can penetrate magnetic fields, such as glass and plastic, and its size and shape are not limited.

[0008] A high-sensitivity capacitive sensor is a capacitive sensor that is highly sensitive to the dielectric constant of a liquid. It can be constructed by using electrodes made of different materials, such as copper and brass.

[0009] Low-sensitivity capacitive sensors are capacitive sensors that are insensitive to the dielectric constant of liquids. They can be constructed by using electrodes made of different materials, such as copper and brass.

[0010] The hardware measurement circuit includes a weak capacitance hardware circuit module and a main control hardware circuit module, as well as other necessary hardware circuit modules such as filters, power supply, Bluetooth, and display. It can be built according to different needs.

[0011] The connecting harness uses ordinary copper wire connections.

[0012] This invention utilizes two capacitive sensors with different sensitivities: One type is a high-sensitivity capacitive sensor, and the other is a low-sensitivity capacitive sensor; By measuring the capacitance values ​​of the two capacitive sensors based on their differences, the real-time height of the liquid and liquid foam can be determined. When the actual height of the liquid and liquid foam changes, the capacitance value changes accordingly, and the height of the liquid and liquid foam calculated from the capacitance value also changes, thus forming a system that can measure and provide feedback in real time.

[0013] There are several ways to implement high-sensitivity and low-sensitivity capacitive sensors. These sensors can be implemented using opposing electrodes or planar electrodes.

[0014] The opposing electrodes are mainly used to construct high-sensitivity and low-sensitivity capacitive sensors by changing the wall thickness of the container or the spacing between the two opposing electrodes. Specifically, by continuously increasing the thickness 1, a low-sensitivity capacitive sensor is obtained, which is very insensitive to the dielectric constant of the liquid being measured; by continuously decreasing the thickness 2, a high-sensitivity capacitive sensor is obtained, which is very sensitive to the dielectric constant of the liquid being measured.

[0015] Planar capacitors can be used to construct high-sensitivity and low-sensitivity capacitive sensors by changing the wall thickness of the container, the spacing between the two electrodes, and the width of the two electrodes. Specifically, by continuously decreasing the spacing 1 and continuously increasing the width 1, a high-sensitivity capacitive sensor is obtained, which is highly sensitive to the dielectric constant of the liquid being measured; by continuously increasing the spacing 2 and continuously decreasing the width 2, a low-sensitivity capacitive sensor is obtained, which is not sensitive to the dielectric constant of the liquid being measured.

[0016] Two capacitive sensors are connected to the hardware measurement circuit via a wiring harness. The height of the liquid and liquid foam is calculated by the software based on the data measured by the hardware circuit.

[0017] Assume the container contains liquid and liquid foam, with the liquid level being... (Unit: mm), the height of the liquid foam is (Unit: mm).

[0018] The capacitance value of a high-sensitivity capacitive sensor is obtained using the following formula:

[0019] in, This is the capacitance value measured in real time by a high-sensitivity capacitive sensor; The liquid coefficient of the high-sensitivity capacitive sensor is the capacitance value contributed by the liquid per 1 mm height in the high-sensitivity capacitive sensor. This coefficient is a pre-calibrated known constant. The liquid foam coefficient of the high-sensitivity capacitive sensor is the capacitance value contributed by liquid foam of 1 mm height in the high-sensitivity capacitive sensor. This coefficient is a pre-calibrated known constant.

[0020] The capacitance value of a low-sensitivity capacitive sensor is obtained using the following formula:

[0021] in, This is the capacitance value measured in real time by a low-sensitivity capacitive sensor. The liquid coefficient of the low-sensitivity capacitive sensor is the capacitance value contributed by the liquid per 1 mm height in the low-sensitivity capacitive sensor. This coefficient is a pre-calibrated known constant. The liquid foam coefficient of the low-sensitivity capacitive sensor is the capacitance value contributed by liquid foam per 1 mm height in the low-sensitivity capacitive sensor. This coefficient is a pre-calibrated known constant.

[0022] By combining these two systems of equations, we can directly calculate... and The values ​​can be displayed directly through software settings or uploaded to the host computer.

[0023] This measuring device is no longer limited to sensing the presence or absence of liquid foam, but can measure the height of liquid foam in real time and provide accurate height values. At the same time, it can also measure the height of the liquid.

[0024] This measuring device is not only suitable for liquids and liquid foams, but also for measuring the height of any two liquids with different dielectric constants, such as pure water and oil. It can measure the height of pure water and the height of oil when the two liquids are mixed together.

[0025] The technical effects and advantages of this invention are as follows: (1) The height of the liquid and liquid foam can be determined in real time by measuring the data from two capacitive sensors; (2) The sensor no longer simply acts as a switch for the presence or absence of foam, but can measure the height of liquid foam in real time, giving the system a very accurate feedback, so that the system can make a judgment and take the next step that is beneficial to itself. (3) This measuring device is also applicable to any two liquids with different dielectric constants. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the measuring device of the present invention implemented by opposing electrodes; Figure 2 This is a schematic diagram illustrating the principle of dielectric constant measurement when two media are present at the opposing electrode. Figure 3 This is a schematic diagram of the measuring device implemented by planar electrodes according to the present invention; Figure 4 This is a schematic diagram illustrating the principle of the penetration depth of a planar electrode. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] I. Example of Opposed Electrode (I) Sensor Structure Construction like Figure 1 As shown, this invention achieves real-time measurement of liquid foam through opposing electrodes. Two different capacitive sensors are constructed using these opposing electrodes: a high-sensitivity capacitive sensor 2 and a low-sensitivity capacitive sensor 3.

[0029] In this embodiment, container 1 is made of glass, which has the characteristic of being able to penetrate magnetic fields, ensuring that the electric field lines of the capacitive sensor can penetrate the wall of container 1 and enter the interior of container 1. Two opposing electrodes are respectively attached to opposite sides of the outer wall of container 1, and the electrodes are made of copper, which has good conductivity and corrosion resistance.

[0030] According to the basic principle of capacitive sensors, the capacitance value of the sensor varies depending on the medium. The formula for calculating the capacitance value of a conventional counter capacitor is as follows:

[0031] in, This is the capacitance value of the opposing capacitor; This refers to the relative coverage area of ​​the electrode plates; The distance between the plates; is the relative permittivity of the dielectric. is the vacuum permittivity.

[0032] From this formula, it can be seen that, under the condition that other factors remain unchanged, the capacitance value... Relative permittivity of the medium between the plates They are directly proportional. Therefore, when the dielectric constant of the medium between the plates changes, the capacitance value increases. The changes will be corresponding, which is the basic principle of using a capacitive sensor to detect changes in the medium.

[0033] (II) Principle of Mixed Dielectric Capacitance Measurement When using the opposing electrode as a capacitance sensor to measure the liquid inside container 1, the capacitance value of the sensor changes with the dielectric constant of the liquid. However, because of the wall thickness of container 1 sandwiched in between, the dielectric constant corresponding to the measured capacitance value is not the dielectric constant of the liquid being measured, but rather the mixed dielectric constant of the liquid being measured and container 1 mixed together.

[0034] like Figure 2 As shown, when two different media exist between the capacitor electrodes (e.g., the wall of container 1 and the liquid / foam inside container 1), the entire capacitor can be considered as a composite capacitor formed by the two media connected in series. The measured dielectric constant is the mixed dielectric constant of the two media, and the capacitance value is calculated using the following formula:

[0035] in, This is the capacitance value of the opposing capacitor; This refers to the relative coverage area of ​​the electrode plates; It is the vacuum permittivity; Let be the dielectric constant of the first medium (such as the wall of container 1); The dielectric constant of the second medium (such as liquid or foam in container 1); The thickness of the first medium (i.e., the thickness of the wall of container 1). The thickness of the second medium.

[0036] When two media are present, assume that the equivalent dielectric constants of the two media are... Then the following relationship is satisfied:

[0037] From the above equation, it can be seen that when two media are present, the equivalent dielectric constant is... It must be smaller than the largest dielectric constant among them. When the thickness of the first medium (the wall of container 1)... The larger the proportion, the higher the equivalent dielectric constant. The closer it gets to the dielectric constant of the container wall 1 The smaller the impact of changes in the internal medium (liquid or foam) on the total capacitance, the lower the sensitivity of the sensor to changes in the internal medium.

[0038] Conversely, when the thickness of the first medium (the wall of container 1) The smaller the proportion, the lower the equivalent dielectric constant. The closer it gets to the dielectric constant of the medium inside container 1 The greater the impact of changes in the internal medium of container 1 on the total capacitance, the higher the sensitivity of the sensor to changes in the internal medium.

[0039] (III) Differentiated Construction of High-Sensitivity and Low-Sensitivity Sensors Based on the above principle, two different capacitive sensors can be constructed by changing the spacing between the opposing capacitor plates and the wall thickness of container 1.

[0040] like Figure 1 As shown, the wall thickness of container 1 corresponding to the high-sensitivity capacitive sensor 2 is thickness 2 (i.e., the thinner wall thickness area), and the wall thickness of container 1 corresponding to the low-sensitivity capacitive sensor 3 is thickness 1 (i.e., the thicker wall thickness area).

[0041] Specifically, the thickness 1 (corresponding to the wall thickness of container 1 at the location of low-sensitivity capacitive sensor 3) is continuously increased, thereby increasing the proportion of container 1 wall in the total dielectric thickness. At this point, the equivalent dielectric constant... Mainly determined by the dielectric constant of the container wall 1 It was determined that the change in dielectric constant of the liquid or foam inside container 1 contributes very little to the total capacitance, thus resulting in a low-sensitivity capacitive sensor 3, which is very insensitive to changes in the dielectric constant of the liquid being measured.

[0042] Similarly, by continuously reducing thickness 2 (corresponding to the wall thickness of container 1 at the location of high-sensitivity capacitive sensor 2), the proportion of container 1 wall in the total dielectric thickness decreases. At this point, the equivalent dielectric constant... Mainly determined by the dielectric constant of the medium inside container 1 It was determined that the change in dielectric constant of the liquid or foam inside container 1 contributes significantly to the total capacitance. Therefore, a highly sensitive capacitive sensor 2 was obtained, which is very sensitive to changes in the dielectric constant of the liquid being measured.

[0043] It should be noted that thickness 1 and thickness 2 can be the difference in wall thickness between different areas of the same container 1, or the difference in wall thickness between two independent containers 1. In actual manufacturing, the local wall thickness can be increased by adding insulating pads or coatings to specific areas of the outer wall of container 1, thereby forming a low-sensitivity sensor area.

[0044] In addition to changing the wall thickness, the sensitivity can also be adjusted by changing the distance between the two opposing electrodes. Specifically, increasing the distance between the opposing electrodes will make the electric field distribution more dispersed, increasing the proportion of electric field lines passing through the wall of container 1, thereby reducing the sensitivity to the internal medium; while decreasing the distance between the opposing electrodes will make the electric field pass through the interior of container 1 more concentrated, thereby increasing the sensitivity to the internal medium.

[0045] (iv) Sensor calibration Before the equipment is put into use, the coefficients need to be determined. , , , Perform pre-calibration.

[0046] The calibration method is as follows: First, fill container 1 with only the material of known height. A pure liquid (free of foam) was used to record the capacitance readings of the high-sensitivity capacitive sensor 2 and the low-sensitivity capacitive sensor 3. and At this point, the foam height... Then we have:

[0047]

[0048] Therefore, it can be calculated that:

[0049]

[0050] Then, inject the known height into container 1. Record the capacitance readings of high-sensitivity capacitive sensor 2 and low-sensitivity capacitive sensor 3 in pure foam (containing no liquid or with zero liquid level). and At this point, the liquid height... Then we have:

[0051]

[0052] Therefore, it can be calculated that:

[0053]

[0054] The above calibration process can be completed before the equipment leaves the factory, and the calibrated results will be used to calibrate the equipment. , , , The values ​​are stored in the memory of the hardware measurement circuit 4 for subsequent real-time measurement and calculation.

[0055] During calibration, it is important to maintain ambient temperature, humidity, and other conditions similar to those of the operating conditions to minimize the impact of environmental factors on calibration accuracy. If significant changes occur in environmental conditions during use, recalibration should be performed periodically to ensure measurement accuracy.

[0056] (v) Real-time measurement and calculation Two capacitive sensors are connected to the hardware measurement circuit 4 via connecting wire harness 5. The data measured by the hardware measurement circuit 4 is used by software to calculate the height of the liquid and liquid foam.

[0057] Assume container 1 contains liquid and liquid foam, with the liquid level being... (Unit: mm), the height of the liquid foam is (Unit: mm). In actual operation, the high-sensitivity capacitive sensor 2 and the low-sensitivity capacitive sensor 3 respectively sense changes in the combined liquid and foam media. The capacitance values ​​of the two sensors are the sum of contributions from the two media (liquid and foam): The capacitance value of the high-sensitivity capacitive sensor 2 is obtained using the following formula:

[0058] in, The capacitance value is measured in real time by the high-sensitivity capacitive sensor 2. The liquid coefficient of the high-sensitivity capacitive sensor 2 is the capacitance value contributed by the liquid per 1 mm height in the high-sensitivity capacitive sensor 2. This coefficient is a known constant that has been pre-calibrated. The liquid foam coefficient of the high-sensitivity capacitive sensor 2 is the capacitance value contributed by liquid foam of 1 mm height in the high-sensitivity capacitive sensor 2. This coefficient is a known constant that has been calibrated in advance.

[0059] The capacitance value of the low-sensitivity capacitive sensor 3 is obtained using the following formula:

[0060] in, The capacitance value is measured in real time by the low-sensitivity capacitive sensor 3. The liquid coefficient of the low-sensitivity capacitive sensor 3 is the capacitance value contributed by the liquid per 1 mm height in the low-sensitivity capacitive sensor 3. This coefficient is a known constant that has been pre-calibrated. The liquid foam coefficient of the low-sensitivity capacitive sensor 3 is the capacitance value contributed by liquid foam of 1 mm height in the low-sensitivity capacitive sensor 3. This coefficient is a known constant that has been pre-calibrated.

[0061] because , , , All have been calibrated and determined to be known constants, and , The known values ​​are acquired in real time by the hardware measurement circuit 4, therefore, these two equations together form a system of two linear equations in two variables. This system of equations contains two equations and two unknowns ( and ), which has a unique solution.

[0062] Solving this system of equations will allow us to directly calculate... and The value:

[0063]

[0064] Calculated and The values ​​can be directly displayed on the display module of the hardware measurement circuit 4 through software settings, or uploaded to a host computer or cloud server through wireless communication modules such as Bluetooth for remote monitoring and data analysis.

[0065] (vi) Real-time feedback and update mechanism The hardware measurement circuit 4 continuously acquires capacitance data from the high-sensitivity capacitive sensor 2 and the low-sensitivity capacitive sensor 3 at a set sampling frequency (e.g., 10 to 100 times per second). Each time a new value is acquired... and After receiving the data, hardware measurement circuit 4 immediately recalculates. and The values ​​enable continuous real-time monitoring of liquid height and liquid foam height.

[0066] When the liquid level in container 1 is... When changes occur (e.g., due to liquid injection or discharge), the dielectric constant of the liquid differs from that of the foam. and All will change. However, because the high-sensitivity capacitive sensor 2 is more sensitive to changes in the liquid, The magnitude of the change is significantly greater than The magnitude of change can be accurately tracked by calculating using a system of simultaneous equations. The changes are reflected.

[0067] Similarly, when the height of the liquid foam in container 1 is... When changes occur (e.g., due to foam formation or defoaming). and Changes will also occur. However, because the low-sensitivity capacitive sensor 3 is almost insensitive to changes in foam ( The values ​​are extremely small, while the high-sensitivity capacitive sensor 2 is more sensitive to changes in foam. (For larger numerical values), the difference can be accurately distinguished by solving the system of equations. The changes.

[0068] The aforementioned real-time feedback mechanism enables the device to continuously output accurate liquid height and liquid foam height data with a millisecond-level response speed, providing real-time and reliable data support for subsequent automatic control (such as automatic addition of defoamer, automatic adjustment of liquid level, etc.).

[0069] II. Planar Electrode Examples (I) Sensor Structure Construction like Figure 3 As shown, this invention achieves real-time measurement of liquid foam using planar electrodes. Two different capacitive sensors are constructed using the planar electrodes: a high-sensitivity capacitive sensor 2 and a low-sensitivity capacitive sensor 3.

[0070] The main difference between a planar electrode and a counter electrode is that the two electrodes of a planar electrode are arranged side by side on the same side of the outer wall of container 1. Electric field lines originate from one of the electrodes, pass through the wall of container 1, enter the interior of container 1, and then return to the other electrode. This configuration is suitable for scenarios where the wall of container 1 is thick or where a counter electrode cannot be installed inside container 1.

[0071] In this embodiment, the planar electrode is fabricated using PCB (Printed Circuit Board) technology, where the electrode pattern is directly printed onto an insulating substrate, which is then attached to the outer wall of container 1. The electrode material is gold-plated brass, which has good conductivity and oxidation resistance.

[0072] (II) Penetration Depth Principle The penetration capability of a planar capacitive sensor is limited; its electric field lines are mainly concentrated in the region near the electrode surface, and the electric field strength gradually decreases with increasing distance. The formula for calculating its penetration capability is as follows:

[0073] in, The penetration thickness of a planar capacitor (i.e., the depth to which an electric field can effectively penetrate and sense changes in the dielectric). The distance between the two planar electrodes; Let be the width of the planar electrode, assuming that the widths of the two electrodes are the same.

[0074] From the above formula, we can see the penetration thickness of the planar capacitive sensor. Spacing between electrodes and electrode width The sum is directly proportional. This means that when the electrode spacing... Increase or electrode width As the electrode spacing increases, the penetration depth of the electric field lines increases, allowing the electric field to reach farther regions; conversely, as the electrode spacing decreases... Reduced or electrode width When the electric field is reduced, the penetration depth of the electric field lines decreases, and the electric field is mainly concentrated near the electrode surface.

[0075] (III) Differentiated Construction of High-Sensitivity and Low-Sensitivity Sensors Based on the aforementioned penetration depth principle, the high-sensitivity capacitive sensor 2 and the low-sensitivity capacitive sensor 3 are constructed by adjusting the width and spacing of the planar electrodes.

[0076] like Figure 3 As shown, the electrode spacing of the high-sensitivity capacitive sensor 2 is 1, and the electrode width is 1; the electrode spacing of the low-sensitivity capacitive sensor 3 is 2, and the electrode width is 2.

[0077] Specifically, by continuously reducing the spacing 1 and continuously increasing the width 1, the penetration thickness is increased. The electric field of the high-sensitivity capacitive sensor 2 is increased, meaning that the electric field can penetrate the wall of container 1 and reach a relatively far area inside container 1, fully sensing the change in dielectric constant of the liquid and foam inside container 1. Therefore, a high-sensitivity capacitive sensor 2 is obtained, which is very sensitive to the dielectric constant of the liquid being measured.

[0078] By continuously increasing the spacing 2 and continuously decreasing the width 2, the penetration thickness is increased. The electric field of the low-sensitivity capacitive sensor 3 is mainly concentrated near the surface of the container wall 1 and cannot effectively penetrate the container wall 1 to enter the interior of the container 1. Therefore, the sensor mainly senses the dielectric constant of the container wall 1 and is almost insensitive to the changes in the dielectric constant of the liquid and foam inside the container 1, thus obtaining a low-sensitivity capacitive sensor 3.

[0079] In practical design, the spacing and width parameters of the electrodes can be optimized through finite element simulation based on the wall thickness of container 1 and the characteristics of the measured medium to achieve the best sensitivity difference. Generally speaking, the penetration depth of the high-sensitivity capacitive sensor 2 should be more than twice the wall thickness of container 1 to ensure that the electric field can fully penetrate into the interior of container 1; the penetration depth of the low-sensitivity capacitive sensor 3 should be less than 0.5 times the wall thickness of container 1 to ensure that the electric field is mainly concentrated inside the wall of container 1.

[0080] (iv) Calibration and Measurement Two capacitive sensors are connected to the hardware measurement circuit 4 via connecting wire harness 5. The data measured by the hardware measurement circuit 4 is used by software to calculate the height of the liquid and liquid foam.

[0081] The calibration method, calculation formula, and solution process for the planar electrode embodiment are exactly the same as those for the counter electrode embodiment. That is, calibration is first performed using pure liquid. and Then, it is obtained through pure foam calibration. and The calibration coefficients are then stored in hardware measurement circuit 4. During actual measurement, the capacitance value is measured and the height is calculated by simultaneously solving the following two sets of equations:

[0082]

[0083] The meanings of each variable and coefficient are exactly the same as in the embodiment of the counter electrode, and will not be repeated here.

[0084] The counter-electrode embodiment is suitable for situations where the container 1 has a thin wall and the electrodes can be installed on both sides of the container 1. It has the advantages of high signal strength and high signal-to-noise ratio, and is suitable for high-precision measurement requirements.

[0085] The planar electrode embodiment is suitable for situations where the container 1 has thick walls and electrodes can only be installed from one side of the container 1. It has the advantages of convenient installation and does not occupy the internal space of the container 1, making it suitable for scenarios where existing containers 1 need to be modified and upgraded.

[0086] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A liquid foam height measuring device, characterized in that, include: Container (1) is used to contain the liquid to be tested and the foam of the liquid to be tested; A high-sensitivity capacitive sensor (2) is disposed on the container (1) for detecting the capacitance value of the medium inside the container (1). The high-sensitivity capacitive sensor (2) is highly sensitive to the dielectric constant of the liquid. A low-sensitivity capacitive sensor (3) is disposed on the container (1) for detecting the capacitance value of the medium inside the container (1). The low-sensitivity capacitive sensor (3) is not sensitive to the dielectric constant of the liquid. The hardware measurement circuit (4) is electrically connected to the high-sensitivity capacitive sensor (2) and the low-sensitivity capacitive sensor (3) respectively via a connecting wire harness (5) to collect the capacitance data of the high-sensitivity capacitive sensor (2) and the low-sensitivity capacitive sensor (3); The hardware measurement circuit (4) measures the capacitance value based on the high-sensitivity capacitive sensor (2). The capacitance value measured by the low-sensitivity capacitive sensor (3) The liquid height can be calculated by solving the following system of equations. and liquid foam height : in, The liquid coefficient of the high-sensitivity capacitive sensor (2) is the capacitance value contributed by the liquid per 1 mm height in the high-sensitivity capacitive sensor (2). The liquid foam coefficient of the high-sensitivity capacitive sensor (2) is the capacitance value contributed by liquid foam of 1 mm height in the high-sensitivity capacitive sensor (2). The liquid coefficient of the low-sensitivity capacitive sensor (3) is the capacitance value contributed by the liquid per 1 mm height in the low-sensitivity capacitive sensor (3). The liquid foam coefficient of the low-sensitivity capacitive sensor (3) is the capacitance value contributed by liquid foam of 1 mm height in the low-sensitivity capacitive sensor (3). The , , , All of these are known constants that have been pre-calibrated.

2. The liquid foam height measuring device according to claim 1, characterized in that, The high-sensitivity capacitive sensor (2) and the low-sensitivity capacitive sensor (3) are implemented using a counter electrode structure; The high-sensitivity capacitive sensor (2) achieves high sensitivity to the dielectric constant of the liquid by reducing the wall thickness of the container (1) to reduce the dielectric thickness between the opposing electrodes. The low-sensitivity capacitive sensor (3) achieves insensitivity to the dielectric constant of the liquid by increasing the wall thickness of the container (1) to increase the dielectric thickness between the opposing electrodes.

3. The liquid foam height measuring device according to claim 1, characterized in that, The high-sensitivity capacitive sensor (2) and the low-sensitivity capacitive sensor (3) are implemented using a counter electrode structure; The high-sensitivity capacitive sensor (2) achieves high sensitivity to the dielectric constant of the liquid by reducing the distance between the two opposing electrodes; The low-sensitivity capacitive sensor (3) achieves insensitivity to the dielectric constant of the liquid by increasing the distance between the two opposing electrodes.

4. The liquid foam height measuring device according to claim 1, characterized in that, The high-sensitivity capacitive sensor (2) and the low-sensitivity capacitive sensor (3) are implemented using a planar electrode structure; The high-sensitivity capacitive sensor (2) achieves high sensitivity to the dielectric constant of the liquid by reducing the distance between the two planar electrodes and increasing the width of the planar electrodes; The low-sensitivity capacitive sensor (3) achieves insensitivity to the dielectric constant of the liquid by increasing the spacing between the two planar electrodes and reducing the width of the planar electrodes.

5. The liquid foam height measuring device according to claim 1, characterized in that, The container (1) is made of glass or plastic material that can penetrate magnetic fields. The shape of the container is not limited and can be various shapes according to its own needs. The surface where the high-sensitivity capacitive sensor (2) and the low-sensitivity capacitive sensor (3) are located can be a plane or a curved surface.

6. The liquid foam height measuring device according to claim 1, characterized in that, The electrodes of the high-sensitivity capacitive sensor (2) and the low-sensitivity capacitive sensor (3) are made of copper or brass, and the shape of the electrodes can be various shapes according to their own needs, such as rectangles, circles, triangles, etc.

7. The liquid foam height measuring device according to claim 1, characterized in that, The hardware measurement circuit (4) includes a weak capacitor hardware circuit module and a main control hardware circuit module, as well as filter, power supply, Bluetooth and display hardware circuit modules configured according to requirements.

8. The liquid foam height measuring device according to claim 1, characterized in that, The connecting wire harness (5) is made of copper wire.

9. A liquid foam height measuring device according to any one of claims 1 to 8, characterized in that, The measuring device is also suitable for measuring the height of any two liquids with different dielectric constants.

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