Liquid level measuring device based on temperature difference demarcation point

Abstract

The invention relates to a liquid level measuring device based on a temperature difference demarcation point. Real-time measurement of the liquid level height of a corresponding application background is achieved. The slender structural member is filled with heat conduction liquid and is mounted perpendicular to the surface of to-be-detected liquid, and the bottom end extends to the bottom of the to-be-detected liquid; the control device controls the heating wire immersed in the heat conduction liquid to heat the heat conduction liquid until the value measured by the first temperature-sensitive resistor reaches the set temperature, the thin and long structural part with small thermal inertia is partially immersed in the liquid, the temperature difference demarcation point is consistent with the liquid level height, the value measured by the second temperature-sensitive resistor is the temperature value of the liquid to be measured, and the temperature difference demarcation point is consistent with the liquid level height. The length of the first temperature-sensitive material resistance wire is consistent with that of the slender structural member, the first temperature-sensitive material resistance wire is immersed in the heat conduction liquid, and two ends are respectively fixed at the top end and the bottom end of the slender structural member; the liquid level height of the liquid to be measured can be determined according to the temperature value measured by the first temperature-sensitive resistor, the temperature value measured by the second temperature-sensitive resistor and the actually measured resistance value of the first temperature-sensitive material resistance wire.

Description

Technical Field

[0001] The present application relates to the field of liquid level measurement, and in particular to a liquid level measurement device based on a temperature difference dividing point. Background Art

[0002] Liquid level measurement has a wide range of applications in modern production and life, covering multiple industries and fields. For example, liquid level measurement technology is also widely used in industries such as oil, natural gas, and food processing for liquid level monitoring of equipment such as storage tanks and reactors. In the field of water treatment, liquid level measurement is used to monitor the liquid level of water bodies such as pools and tanks, providing accurate data support for water resource management and water quality control. In terms of hydrological measurement, liquid level measurement provides real-time monitoring and early warning of water level changes, allowing timely detection and response to abnormal water level changes, providing technical support for flood control and drought relief, and water resource management. Liquid level measurement is also widely used for liquid level monitoring in rivers, lakes, and seas, urban water supply systems, drainage networks, and household water tanks, providing support for ensuring the rational allocation and use of water resources and preventing urban waterlogging. In addition, liquid level sensors are also used in household appliances such as smart toilets, water heaters, and coffee machines, automatically detecting water levels and controlling water addition, improving the intelligence of the equipment and user experience.

[0003] With the rapid development of industrial automation and intelligent manufacturing, the requirements for the accuracy and reliability of liquid level measurement are becoming increasingly stringent. Traditional liquid level measurement methods, such as water gauge measurement, buoyancy measurement, pressure measurement, capacitance measurement, microwave reflection wave measurement, ultrasonic reflection measurement, infrared reflection measurement, and magnetic float and bubble measurement, can meet measurement needs to a certain extent. However, these methods are limited in some applications that are not suitable for human operation, such as rivers, urban water supply, and drainage pipes. Summary of the Invention

[0004] The present application provides a liquid level measurement device based on a temperature difference dividing point, which realizes liquid level measurement in an application context requiring automatic collection of liquid level data.

[0005] The technical solution of this application is:

[0006] A liquid level measuring device based on a temperature difference dividing point, comprising:

[0007] A slender structural member for partially inserting into the liquid to be tested, wherein the inner cavity of the slender structural member is filled with a heat-conducting liquid;

[0008] a control device, a heating wire and a first temperature-sensitive material resistance wire connected to the control device by a wire, passing through the elongated structural member and immersed in the heat-conductive liquid, with ends of the heating wire and the first temperature-sensitive material resistance wire contacting the bottom of the inner cavity of the elongated structural member;

[0009] a first temperature-sensitive resistor and a second temperature-sensitive resistor connected to the control device, wherein the first temperature-sensitive resistor is arranged on the top of the heat-conducting liquid and the second temperature-sensitive resistor is arranged on the bottom of the heat-conducting liquid;

[0010] When performing liquid level measurement, one end of the slender structural member is inserted into the liquid to be measured, and the control device controls the heating wire to heat the heat-conducting liquid; after the heat-conducting liquid is heated, the liquid level of the liquid to be measured is determined based on the real-time temperatures detected by the first temperature-sensitive resistor and the second temperature-sensitive resistor respectively and the measured resistance of the first temperature-sensitive material resistance wire.

[0011] Preferably, the step of determining the liquid level of the liquid to be measured according to the real-time temperatures detected by the first temperature-sensitive resistor and the second temperature-sensitive resistor respectively and the measured resistance of the first temperature-sensitive material resistance wire includes:

[0012] According to the formula:

[0013]

[0014] Calculate the liquid level l of the liquid to be measured;

[0015] Among them, R1 is the measured resistance of the first temperature-sensitive material resistance wire, R2 is the resistance of the first temperature-sensitive material resistance wire calculated at the temperature measured by the first temperature-sensitive resistor, R3 is the resistance of the first temperature-sensitive material resistance wire calculated at the temperature measured by the second temperature-sensitive resistor, and L is the length of the first temperature-sensitive material resistance wire.

[0016] Preferably, a second temperature-sensitive material resistance wire connected to the control device by a wire is installed at the top end of the elongated structural member and immersed in the heat-conducting liquid;

[0017] The second temperature-sensitive material resistance wire is made of the same material and has the same diameter as the first temperature-sensitive material resistance wire;

[0018] When performing liquid level measurement, one end of the slender structural member is inserted into the liquid to be measured, and the control device controls the heating wire to heat the heat-conducting liquid; after the heat-conducting liquid is heated, the liquid level of the liquid to be measured is determined based on the real-time temperature detected by the second temperature-sensitive resistor and the measured resistances of the first temperature-sensitive material resistance wire and the second temperature-sensitive material resistance wire.

[0019] Preferably, the second temperature-sensitive material resistance wire has the same length as the first temperature-sensitive material resistance wire, and the step of determining the liquid level of the liquid to be measured according to the real-time temperature detected by the second temperature-sensitive resistor and the measured resistances of the first temperature-sensitive material resistance wire and the second temperature-sensitive material resistance wire includes:

[0020] By formula:

[0021]

[0022] Calculate the liquid level l of the liquid to be measured, where R1 is the measured resistance of the first temperature-sensitive material resistance wire, R3 is the resistance of the first temperature-sensitive material resistance wire calculated at the temperature measured by the second temperature-sensitive resistor, R4 is the measured resistance of the second temperature-sensitive material resistance wire, and L is the length of the first temperature-sensitive material resistance wire.

[0023] Preferably, a second temperature-sensitive material resistance wire connected to the control device by a wire is installed at the top of the elongated structural member and immersed in the heat-conducting liquid; the second temperature-sensitive material resistance wire is made of the same material and has the same diameter as the first temperature-sensitive material resistance wire;

[0024] A third temperature-sensitive material resistance wire connected to the control device by a wire passes through the elongated structure and is immersed in the heat-conducting liquid, and an end of the third temperature-sensitive material resistance wire is arranged at the bottom of the inner cavity of the elongated structure;

[0025] A fourth temperature-sensitive resistance wire connected to the control device by a wire is installed at the top of the elongated structure and immersed in the heat-conducting liquid; the fourth temperature-sensitive resistance wire is made of the same material and has the same diameter as the first temperature-sensitive resistance wire;

[0026] When performing liquid level measurement, one end of the slender structural member is inserted into the liquid to be measured, and the control device controls the heating wire to heat the heat-conducting liquid; after the heat-conducting liquid is heated, the liquid level of the liquid to be measured is determined based on the measured resistances of the first temperature-sensitive material resistance wire, the second temperature-sensitive material resistance wire, the third temperature-sensitive material resistance wire, and the fourth temperature-sensitive material resistance wire.

[0027] Preferably, the liquid level of the liquid to be measured is determined according to the measured resistances of the first temperature-sensitive material resistance wire, the second temperature-sensitive material resistance wire, the third temperature-sensitive material resistance wire, and the fourth temperature-sensitive material resistance wire:

[0028] By formula:

[0029]

[0030] Determine the output voltage V of the bridge in which the first temperature-sensitive material resistance wire, the second temperature-sensitive material resistance wire, the third temperature-sensitive material resistance wire, and the fourth temperature-sensitive material resistance wire are located; wherein R1 is the measured resistance of the first temperature-sensitive material resistance wire, R2 is the measured resistance of the second temperature-sensitive material resistance wire, R3 is the measured resistance of the third temperature-sensitive material resistance wire, R4 is the measured resistance of the fourth temperature-sensitive material resistance wire, and U0 is the supply voltage of the bridge in which the first temperature-sensitive material resistance wire, the second temperature-sensitive material resistance wire, the third temperature-sensitive material resistance wire, and the fourth temperature-sensitive material resistance wire are located;

[0031] By formula:

[0032] l=kV

[0033] Calculate the liquid level l of the liquid to be measured; where k is the preset proportional coefficient.

[0034] The present application also provides a liquid level measurement device based on a temperature difference dividing point, comprising:

[0035] A slender structural member used to partially insert into the liquid to be tested, wherein the inner cavity of the slender structural member is filled with a heat-conducting liquid and the whole has a small thermal inertia;

[0036] a control device, wherein a heating wire connected to the control device by a wire passes through the elongated structure and is immersed in the heat-conducting liquid;

[0037] Infrared ray blocking rings, a plurality of which are evenly spaced and sleeved on the outside of the elongated structural member;

[0038] an infrared thermographic device disposed outside the liquid to be measured, which captures an infrared image directed toward the elongated structural member, and determines the position of the liquid level-temperature boundary based on the infrared image captured by the infrared thermographic device and in combination with the shielding ring to obtain the liquid level of the liquid to be measured;

[0039] The spacing between the infrared blocking rings is equivalent to the number of millimeters corresponding to the number of imaging pixels of the infrared thermographic imaging device used.

[0040] Preferably, the heating wire is a silicone heating wire or a carbon fiber heating wire.

[0041] Preferably, the heat transfer liquid is fluorinated liquid or transformer oil, and the elongated structural member is a thin-walled stainless steel tube.

[0042] Preferably, the first temperature-sensitive material resistance wire, the second temperature-sensitive material resistance wire, the third temperature-sensitive material resistance wire and the fourth temperature-sensitive material resistance wire are made of materials with a positive temperature coefficient of resistance or a negative temperature coefficient of resistance.

[0043] The beneficial effects of this application are:

[0044] A slender structural member serves as the measuring element, with a heat-conducting liquid injected into its inner cavity. This liquid is heated and its temperature monitored by a heating wire and temperature-sensitive resistor wire in a control device, enabling precise automatic measurement of the liquid level. This device is particularly suitable for environments unsuitable for human operation, such as rivers, urban water supply lines, and drainage pipes. These level measurement devices are independent of lighting conditions and therefore maintain stable level measurement performance in all lighting environments. Furthermore, since the temperature-sensitive resistor wire, heating wire, and temperature-sensitive resistor are all located within the slender structural member, they are not directly exposed to the liquid being measured. Interference from the liquid prevents the operation of the components within the slender structural member from being affected, resulting in excellent anti-interference capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a schematic diagram of the liquid level measurement principle;

[0046] Figure 2 for Figure 1 A partial enlarged schematic diagram;

[0047] Figure 3 Schematic diagram of the liquid level measurement principle based on the temperature sensitive effect;

[0048] Figure 4 Schematic diagram of a liquid level measurement device based on a temperature difference dividing point involved in Example 1 of the present application;

[0049] Figure 5 Schematic diagram of a liquid level measurement device based on a temperature difference dividing point involved in Example 2 of the present application;

[0050] Figure 6 Schematic diagram of a liquid level measurement device based on a temperature difference dividing point involved in Example 3 of the present application;

[0051] Figure 7 Schematic diagram of a liquid level measurement device based on a temperature difference dividing point involved in the fourth embodiment of the present application;

[0052] Figure 8 This is a schematic diagram of the circuit principles involved in Example 5 of the present application;

[0053] Figure 9 This is a schematic diagram of the liquid level measurement device based on the temperature difference dividing point involved in Example 5 of the present application. DETAILED DESCRIPTION

[0054] To facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings. The detailed description is complete, but it should not be construed as limiting the scope of the present invention. Obvious variations and alternative forms of the following examples are all within the scope of protection of this patent.

[0055] refer to Figure 3 and Figure 4 In the first embodiment of the present application, a liquid level measurement device based on a temperature difference dividing point is provided, comprising:

[0056] A slender structural member 1, wherein a heat-conducting liquid 11 is injected into the inner cavity of the slender structural member 1;

[0057] a control device 2, a heating wire 21 and a first temperature-sensitive material resistance wire 22 connected to the control device 2 passing through the slender structural member 1 and inserted into the heat-conducting liquid 11, with the ends of the heating wire 21 and the first temperature-sensitive material resistance wire 22 contacting the bottom of the inner cavity of the slender structural member 1;

[0058] A first temperature-sensitive resistor 23 and a second temperature-sensitive resistor 24 connected to the control device 2 , wherein the first temperature-sensitive resistor 23 is disposed on the top of the heat-conducting liquid 11 , and the second temperature-sensitive resistor 24 is disposed on the bottom of the heat-conducting liquid 11 ;

[0059] When measuring the liquid level, one end of the slender structural member 1 is inserted into the liquid 3 to be measured, and the control device 2 controls the heating wire 21 to heat the heat-conducting liquid 11 until the temperature measured by the first thermistor 23 reaches the set temperature (i.e., the temperature measured by the first thermistor 23 is 30°C higher than the temperature of the second thermistor 24). After the heat-conducting liquid 11 is heated, the liquid level of the liquid 3 to be measured is determined based on the real-time temperatures detected by the first thermistor 23 and the second thermistor 24, respectively, and the measured resistance of the first temperature-sensitive material resistance wire 22.

[0060] In the first embodiment, the overall length of the slender structural member 1 is greater than the liquid level range of the liquid to be measured 3. Therefore, it is necessary to verify the slender structural member 3 that is higher than the historical measured liquid level based on the historical measured liquid level of the liquid to be measured 3. The slender structural member 1 is made of, for example, a stainless steel tube. It is hollow inside, with a sealed bottom end and an unsealed top end, which can allow cables to pass through. When the heating wire 21 and the first temperature-sensitive material resistance wire 22 are assembled, the top end of the slender structural member 1 is sealed by an insulating part (such as a sealing plug, a sealing cover, etc.). The hollow inner cavity of the slender structural member 1 is injected with a heat-conducting liquid 11, so that the slender structural member 1 has a small thermal inertia and can be quickly heated to a predetermined temperature higher than the ambient temperature under the heating of its built-in heating wire 21.

[0061] The control device 2 has a built-in power supply circuit and related control circuits. The control device 2 is connected to the heating wire 21 and the first temperature-sensitive material resistance wire 22 through conductive wires with good temperature stability.

[0062] During assembly, one end of the heating wire 21 and the first temperature-sensitive material resistance wire 22 are fixed to the insulating part assembled at the top of the slender structural member 1, and are extended axially along the slender structural member 1 to the bottom sealed end of the slender structural member 1 and fixed (for example, by gluing and fixing with adhesive, etc.), and the heating wire 21 and the first temperature-sensitive material resistance wire 22 are immersed in the heat conduction liquid 11 as a whole.

[0063] When liquid level measurement is required using the liquid level measuring device, the slender structural member 1 is inserted into the liquid 3 to be measured, perpendicular to the liquid surface of the liquid 3, with the bottom end of the slender structural member 1 aligned with the bottom of the liquid 3. When the liquid level of the liquid 3 to be measured is not zero, the slender structural member 3 is partially or completely immersed in the liquid 3 to be measured. The top end of the slender structural member 1 is fixed to a device floating in the liquid 3 to be measured, or the top end of the slender structural member 1 is fixed to a fixed environmental object (such as a tree, bridge pier, etc.) in the environment surrounding the liquid 3 to be measured.

[0064] The first temperature-sensitive resistor 23 is mounted on a sealing component provided at the unsealed end of the slender structural member 1 , and the second temperature-sensitive resistor 24 is mounted on the inner sealed end of the slender structural member 1 .

[0065] The control device 2 controls the heating wire 21 to heat the heat-conducting liquid 11. The first temperature-sensitive resistor 23 and the second temperature-sensitive resistor 24 respectively detect the real-time temperature inside the two ends of the slender structural member 1. Since the lower end of the slender structural member 1 is immersed in the liquid 3 to be measured and has a small thermal inertia, the temperature difference demarcation point of the heat-conducting liquid 11 inside the slender structural member 1 is basically consistent with the liquid level height of the liquid 3 to be measured. The temperature value measured by the second temperature-sensitive resistor 24 is equivalent to the temperature value of the liquid 3 to be measured. The measured resistance value of the first temperature-sensitive material resistance wire 22 will change with the liquid level. Therefore, the liquid level of the liquid 3 to be measured can be determined by the temperature values ​​measured by the first temperature-sensitive resistor 23, the temperature values ​​measured by the second temperature-sensitive resistor 24, and the measured resistance value of the first temperature-sensitive material resistance wire 22.

[0066] When not heated, the values ​​measured by the first temperature-sensitive resistor 23 and the second temperature-sensitive resistor 24 are both ambient temperature values.

[0067] By injecting a heat-conducting liquid 11 into the slender structural member 1, heating the heat-conducting liquid 11 using a heater wire 21 connected to the control device 2, and monitoring the temperature of the heat-conducting liquid 11 using a first temperature-sensitive material resistance wire 22, precise level measurement of the liquid 3 to be measured is achieved. When one end of the slender structural member 1 is inserted into the liquid 3 to be measured, the heater wire 21 heats the heat-conducting liquid 11, while the first temperature-sensitive resistor 23 and the second temperature-sensitive resistor 24 respectively detect the real-time temperature at the top and bottom of the heat-conducting liquid 11. Simultaneously, the first temperature-sensitive material resistance wire 22 monitors the actual resistance. By comprehensively analyzing this data, the liquid level measurement device can accurately determine the liquid level of the liquid to be measured, thereby providing an efficient and reliable automatic liquid level monitoring solution for applications such as industrial process control and environmental monitoring. It is particularly suitable for environments where liquid level measurement is not suitable for manual operation. Furthermore, this liquid level measurement method is independent of lighting conditions, thus maintaining stable level measurement performance in all lighting environments. In addition, since the first temperature-sensitive material resistance wire 22, the heating wire 21, the first temperature-sensitive resistor 23 and the second temperature-sensitive resistor 24 are all arranged inside the slender structural member 1, they will not be directly exposed to the liquid 3 to be measured, and the operation of the devices inside the slender structural member 1 will not be affected by interference from the liquid 3 to be measured. Therefore, the liquid level measuring device has good anti-interference ability.

[0068] In the first embodiment, a section of thin-walled stainless steel pipe is used as the main body of the slender structural member 1 according to the liquid level measurement range; the excellent thermal conductivity and stable physical properties of the thin-walled stainless steel pipe enable it to quickly respond to temperature changes of the heat-conducting liquid 11, thereby achieving high-precision liquid level measurement.

[0069] In the first embodiment, the heat-conducting liquid 11 is fluorinated liquid or transformer oil. Both fluorinated liquid and transformer oil have good heat-conducting properties, which help to transfer heat quickly and evenly, thereby improving the response speed and accuracy of liquid level measurement.

[0070] The control device 2 is responsible for controlling the operation of the heating wire 21, reading the resistance value of the first temperature-sensitive material resistance wire 22, processing the signals of the first temperature-sensitive resistor 23 and the second temperature-sensitive resistor 24, and calculating the liquid level. The structure of the control device 2 includes:

[0071] A power module, which provides power required by the control device 2 and is, for example, a battery;

[0072] A heating control module is responsible for controlling the power output of the heating wire 21 to maintain stable heating of the heat transfer liquid 11; the heating control module is, for example, a PID controller or other type of feedback control system to accurately control the temperature;

[0073] A signal conditioning circuit receives the resistance signal from the first temperature-sensitive material resistance wire 22 and converts it into a voltage or current signal. The signal conditioning circuit includes, for example, an amplifier, a filter, and an analog-to-digital converter (ADC);

[0074] The temperature sensor interface receives the signal from the first temperature-sensitive resistor 23 and converts it into a usable digital signal;

[0075] The microprocessor or microcontroller, serving as the brain of the control device, is responsible for processing all input signals, executing the liquid level calculation algorithm, and controlling the operation of the heating wire 21 and the first temperature-sensitive material resistance wire 22 .

[0076] The first and second thermistors 23, 24 are, for example, temperature sensors. When the elongated structural member 1 is inserted into the liquid 3 to be measured, heat exchange occurs between the heat-conducting liquid 11 and the liquid 3 to be measured, causing the temperatures at the top and bottom of the heat-conducting liquid 11 to change. By comparing the temperatures detected by the first and second thermistors 23, 24, that is, comparing the temperatures at the top and bottom of the heat-conducting liquid 11, the liquid level of the liquid 3 to be measured can be inferred.

[0077] A heating wire 21, made of either silicone or carbon fiber, is placed axially along the elongated structural member 1. After the heating wire 21 and the first temperature-sensitive resistance wire 22 are arranged, one end of the thin-walled stainless steel tube is sealed and a high-performance heat-conducting liquid 11 is injected from the other end to ensure low thermal inertia for the elongated structural member 1 as a whole.

[0078] Combine Figure 1 and Figure 2 During operation, a slender structural member 1 is immersed in the test liquid 3 at one end, perpendicular to the liquid surface, while the other end is exposed to the surrounding environment, typically air. To create a temperature difference, a heat-conducting liquid 11 within the slender structural member 1 is heated to a temperature significantly higher than that of the test liquid 3. Because the heat-conducting liquid 11 and the surrounding air surrounding the slender structural member 1 have significantly different thermal conductivity coefficients, if the thermal inertia of the slender structural member 1 is low, the temperature of the heat-conducting liquid 11 outside the test liquid 3 is significantly higher than that of the portion immersed in the test liquid 3. The heat-conducting liquid 11 within the test liquid 3 maintains a substantially consistent temperature with the test liquid 3, forming a temperature difference boundary at the liquid surface.

[0079] Investigate the temperature dividing point and zoom in on the part. Figure 2As shown within the circle, the slender structural member 1 has a temperature transition zone perpendicular to the surface of the liquid 3 being measured. Above this transition zone is the target temperature T1 for heating the slender structural member 1, while below it is a temperature T2 close to the temperature of the liquid 3 being measured. The axial length of the temperature transition zone along the slender structural member 1 affects the accuracy of liquid level measurement. Therefore, selecting the appropriate material for the slender structural member 1 and controlling the temperature difference can improve measurement accuracy.

[0080] In the first embodiment of the present application, the step of determining the liquid level of the liquid 3 to be measured according to the real-time temperatures detected by the first temperature-sensitive resistor 23 and the second temperature-sensitive resistor 24 and the measured resistance of the first temperature-sensitive material resistance wire 22 includes:

[0081] According to the formula:

[0082]

[0083] Calculate the liquid level l of the liquid to be measured;

[0084] Among them, R1 is the measured resistance of the first temperature-sensitive material resistance wire, R2 is the resistance of the first temperature-sensitive material resistance wire 22 calculated based on the temperature detected by the first temperature-sensitive resistor 23, R4 is the resistance of the first temperature-sensitive material resistance wire 22 calculated based on the temperature detected by the second temperature-sensitive resistor 24, and L is the length of the first temperature-sensitive material resistance wire 22.

[0085] Within a certain temperature difference range, the resistivity of the first temperature-sensitive material resistance wire 22 has a linear relationship with temperature. Assume that the temperature of the upper half detected by the first temperature-sensitive resistor 23 is T1, and the temperature of the lower half detected by the second temperature-sensitive resistor 24 is T2; when the temperatures are T1 and T2 respectively, the resistances of the first temperature-sensitive material resistance wire 22 are R1 and R2, and the length of the first temperature-sensitive material resistance wire is L; and the length of the elongated structural member 1 immersed in the liquid is l; then the actual resistance value R of the first temperature-sensitive material resistance wire 22 is between R1 and R2. When the first temperature-sensitive material resistance wire 22 is completely immersed in the liquid 3 to be measured, R = R2. When the first temperature-sensitive material resistance wire 22 is completely exposed outside the liquid 3 to be measured, R = R1. The measured resistance R value of the first temperature-sensitive material resistance wire 22 can be used to calculate the liquid level l of the liquid 3 to be measured.

[0086] The cross-sectional area and length of the first temperature-sensitive material resistance wire 22 are known values.

[0087] The relationship between the resistance R of the temperature-sensitive material resistance wire at different temperatures and the temperature change can be expressed by the following formula:

[0088] R=R0×(1+α×ΔT)

[0089] in:

[0090] R is the resistance value of the temperature-sensitive material resistance wire at temperature T;

[0091] R0 is the initial resistance at the reference temperature; the resistance value of the first temperature-sensitive material resistance wire 22 is measured at the reference temperature (usually 0°C or 25°C), and this value is called the initial resistance R0;

[0092] α is the resistance temperature coefficient of the first temperature-sensitive material resistance wire 22;

[0093] ΔT is the temperature change relative to a reference temperature, i.e., T-T0.

[0094] By using the above formula, the resistance R1 of the first temperature-sensitive material resistance wire 22 can be calculated according to the temperature detected by the first temperature-sensitive resistor 23 , and the resistance R2 of the first temperature-sensitive material resistance wire 22 can be calculated according to the temperature detected by the second temperature-sensitive resistor 24 .

[0095] The first temperature-sensitive resistance wire 22 is made of a material with a positive or negative temperature coefficient of resistance. For example, nickel-chromium alloy Ni80Cr20, which has a temperature coefficient of resistance of 0.004 / °C, can achieve a high resolution due to the temperature difference between the high-temperature zone and the low-temperature zone being 20-50°C.

[0096] The liquid level measuring device of the first embodiment can realize automatic measurement of the liquid level.

[0097] In the liquid level measuring device of the first embodiment, since the resistor R2 and the resistor R3 need to be calculated based on the temperature measured by the first temperature-sensitive resistor 23 and the temperature measured by the second temperature-sensitive resistor 24, respectively, the result obtained by the calculation method has a certain error. In order to eliminate some technical errors, the second embodiment of the present application adds a second temperature-sensitive material resistance wire 25 on the basis of the first embodiment. Figure 5 A second temperature-sensitive material resistance wire 25 connected to the control device 2 is installed at the top of the elongated structural member 1 and immersed in the heat-conducting liquid 11; the second temperature-sensitive material resistance wire 25 and the first temperature-sensitive material resistance wire 22 are made of the same material and have the same diameter;

[0098] When performing liquid level measurement, one end of the slender structural member 1 is inserted into the liquid 3 to be measured, and the control device 2 controls the heating wire 21 to heat the heat-conducting liquid 11; after the heat-conducting liquid 11 is heated, the liquid level of the liquid 3 to be measured is determined based on the temperature measured by the second temperature-sensitive resistor 24 and the measured resistances of the first temperature-sensitive material resistance wire 22 and the second temperature-sensitive material resistance wire 25.

[0099] When the liquid level measuring device is in operation, the heating wire 21 is used to heat the slender structural member 1. Since the lower portion of the slender structural member 1 is immersed in the liquid 3 to be measured, the slender structural member 1 is divided into two parts with different temperatures. The temperature of the upper half is relatively high, which is called the high temperature zone; the temperature of the lower half is relatively low, which is called the low temperature zone. Since the thin-walled stainless steel tube of the slender structural member 1 is filled with high-performance heat-conducting liquid 11, the remaining parts have relatively uniform temperatures except near the temperature dividing point. The temperatures of the two parts can be measured using the first and second thermistors 23 and 24, respectively. The heating temperature of the heating wire 21 is controlled by the temperature values ​​detected by the first and second thermistors 23 and 24. When the temperature difference between the first and second thermistors 23 and 24 reaches 30° or more, the heating of the heating wire 21 is completed.

[0100] According to actual needs, the length of the second temperature-sensitive material resistance wire 25 and the first temperature-sensitive material resistance wire 22 can be set to be the same or different.

[0101] When the second temperature-sensitive material resistance wire 25 has the same length as the first temperature-sensitive material resistance wire 22, the second temperature-sensitive material resistance wire 25 is wound into a coil with a smaller volume. At this time, according to the formula:

[0102]

[0103] Calculate the liquid level l of the liquid to be measured, where R1 is the measured resistance of the first temperature-sensitive material resistance wire 22, R3 is the resistance of the first temperature-sensitive material resistance wire 22 calculated at the temperature measured by the second temperature-sensitive resistor 24, R4 is the measured resistance of the second temperature-sensitive material resistance wire 25, and L is the length of the first temperature-sensitive material resistance wire 22.

[0104] When the length of the second temperature-sensitive material resistance wire 25 is different from that of the first temperature-sensitive material resistance wire 22, the liquid level l of the liquid 3 to be measured is calculated based on the relationship between the length of the second temperature-sensitive material resistance wire 25 and the length of the first temperature-sensitive material resistance wire 22. For example, when the length of the second temperature-sensitive material resistance wire 25 is 1 / 2 of the length of the first temperature-sensitive material resistance wire 22, the formula is:

[0105]

[0106] Calculate the liquid level l of the liquid to be measured, where R1 is the measured resistance of the first temperature-sensitive material resistance wire 22, R3 is the resistance of the first temperature-sensitive material resistance wire 22 calculated at the temperature measured by the second temperature-sensitive resistor 24, R4 is the measured resistance of the second temperature-sensitive material resistance wire 25, and L is the length of the first temperature-sensitive material resistance wire 22.

[0107] When the length of the second temperature-sensitive material resistance wire 25 is 1 / 4 of the first temperature-sensitive material resistance wire 22, then, according to the formula:

[0108]

[0109] Calculate the liquid level l of the liquid to be measured, where R1 is the measured resistance of the first temperature-sensitive material resistance wire 22, R3 is the resistance of the first temperature-sensitive material resistance wire 22 calculated at the temperature measured by the second temperature-sensitive resistor 24, R4 is the measured resistance of the second temperature-sensitive material resistance wire 25, and L is the length of the first temperature-sensitive material resistance wire 22.

[0110] Compared with the calculation method in Example 1, this calculation method only needs to calculate the resistance R3 of the first temperature-sensitive material resistance wire 22 calculated at the temperature measured by the second temperature-sensitive resistor 24, which reduces one resistance value calculation, can eliminate part of the calculation error, and improve the liquid level measurement accuracy.

[0111] The second temperature-sensitive material resistance wire 25 is made of a material with a positive temperature coefficient of resistance or a negative temperature coefficient of resistance, for example, a nickel-chromium alloy Cr20Ni80 or Cr20Ni35 with a positive temperature coefficient of resistance.

[0112] Although the calculation error can be partially eliminated in the second embodiment, a resistance value still needs to be calculated. Therefore, in the third embodiment of the present application, a third temperature-sensitive material resistance wire 26 is added on the basis of the second embodiment. Figure 6 The third temperature-sensitive material resistance wire 26 connected to the control device 2 passes through the slender structural member 1 and is immersed in the heat-conducting liquid 11, and the end of the third temperature-sensitive material resistance wire 26 is arranged at the bottom of the inner cavity of the slender structural member 1. At this time, an insulated wire with good temperature stability needs to be extended into the inner cavity of the slender structural member 1 to connect the third temperature-sensitive material resistance wire 26.

[0113] The third temperature-sensitive material resistance wire 26 , the second temperature-sensitive material resistance wire 25 and the first temperature-sensitive material resistance wire 21 are made of the same material and have the same diameter.

[0114] Similarly, the length of the third temperature-sensitive material resistance wire 26 can be set to be the same as or different from the length of the first temperature-sensitive material resistance wire 22 as required.

[0115] When the length of the third temperature-sensitive material resistance wire 26 is set to be the same as the length of the first temperature-sensitive material resistance wire 22, the third temperature-sensitive material resistance wire 26 is wound into a coil with a smaller volume. Therefore, the formula:

[0116]

[0117] Calculate the liquid level l of the liquid 3 to be measured, where R1 is the measured resistance of the first temperature-sensitive material resistance wire 22, R4 is the measured resistance of the second temperature-sensitive material resistance wire 25, R5 is the measured resistance of the third temperature-sensitive material resistance wire 26, and L is the length of the first temperature-sensitive material resistance wire 22.

[0118] In this third embodiment, all parameters required for calculating the liquid level 1 of the liquid 3 to be measured are actually measured values, which can completely eliminate errors caused by calculation and reduce the processing process.

[0119] Reference Figure 7 In the fourth embodiment of the present application, another configuration of a liquid level measurement device based on a temperature difference dividing point is provided, which includes:

[0120] A second temperature-sensitive material resistance wire 25 connected to the control device 2 is installed at the top of the elongated structural member 11 and immersed in the heat-conducting liquid 11; the second temperature-sensitive material resistance wire 25 and the first temperature-sensitive material resistance wire 22 have the same material and diameter;

[0121] A third temperature-sensitive material resistance wire 26 connected to the control device 2 passes through the slender structural member 1 and is immersed in the heat-conducting liquid 11, and an end of the third temperature-sensitive material resistance wire 26 is arranged at the bottom of the inner cavity of the slender structural member 1;

[0122] A fourth temperature-sensitive material resistance wire 27 connected to the control device 3 is installed at the top of the elongated structural member 2 and immersed in the heat-conducting liquid 11; the fourth temperature-sensitive material resistance wire 27 is made of the same material and has the same diameter as the first temperature-sensitive material resistance wire 22;

[0123] When performing liquid level measurement, one end of the slender structural member 1 is inserted into the liquid 3 to be measured, and the control device 2 controls the heating wire 21 to heat the heat-conducting liquid 11; after the heat-conducting liquid 11 is heated, the liquid level of the liquid 3 to be measured is determined based on the measured resistances of the first temperature-sensitive material resistance wire 22, the second temperature-sensitive material resistance wire 25, the third temperature-sensitive material resistance wire 26, and the fourth temperature-sensitive material resistance wire 27.

[0124] A first temperature-sensitive resistor 23 is installed at the top of the elongated structural member 1, and a second temperature-sensitive resistor 24 is installed at the bottom. During operation, the heat-conducting liquid 11 within the elongated structural member 1 is heated by the heating wire 21. Since a portion of the elongated structural member 1 is immersed in the liquid 3 to be measured, the entire elongated structural member 1 is divided into two regions with different temperatures: the upper region, which has a relatively high temperature, and the lower region, which has a relatively low temperature, known as the low temperature region. Because the thin-walled stainless steel tube of the elongated structural member 1 is filled with high-performance heat-conducting liquid 11, the remaining regions have a relatively uniform temperature, except near the temperature boundary. The temperatures of the two regions can be measured using the first temperature-sensitive resistor 23 and the second temperature-sensitive resistor 24, respectively. During operation, the high temperature region is at T1, and the low temperature region is at T2, with a temperature difference between the two regions maintained at 30°C and 50°C.

[0125] Reference Figure 8 , the liquid level measuring device in the fifth embodiment uses 4 temperature-sensitive material resistance wires. Among them, the second temperature-sensitive material resistance wire 25 and the fourth temperature-sensitive material resistance wire 27 are installed on the top of the slender structure 1, the installation position is higher than the maximum liquid level measurement height, and immersed in the heat-conducting liquid 11. The second temperature-sensitive material resistance wire 25 and the fourth temperature-sensitive material resistance wire 27 are respectively Figure 8 R1 and R4 in; the third temperature-sensitive material resistance wire 26 is installed at the bottom of the elongated structure 1, corresponding to Figure 8 R3 in the figure is immersed in the heat-conducting liquid 11; the length of the first temperature-sensitive material resistance wire 22 is consistent with the length of the slender structure 1, and it is immersed in the heat-conducting liquid 11. Its two ends are respectively fixed to the top and bottom ends of the slender structure 11. Its resistance value changes with the liquid level height. Figure 8 R2 in.

[0126] The four temperature-sensitive resistance wires are made of the same material, have the same length and diameter; the second temperature-sensitive resistance wire 25 , the third temperature-sensitive resistance wire 26 , and the fourth temperature-sensitive resistance wire 27 are wound into a coil with a smaller volume.

[0127] The output voltage V of the bridge is calculated using the formula:

[0128]

[0129] The output voltage V of the bridge can be determined, where U0 is the power supply voltage of the bridge, R1 is the measured resistance of the first temperature-sensitive material resistance wire 22, R2 is the measured resistance of the second temperature-sensitive material resistance wire 25, R3 is the measured resistance of the third temperature-sensitive material resistance wire 26, and R4 is the measured resistance of the fourth temperature-sensitive material resistance wire 27.

[0130] Furthermore, when the liquid level of the liquid to be measured 3 is zero, R2=R3, and V=0;

[0131] When the liquid level of the liquid to be measured 3 reaches the maximum, R2=R1, and V reaches the maximum value:

[0132]

[0133] Using DC power supply, U0 is the power supply voltage, V is the bridge output voltage, and has a linear relationship with the liquid level height l of the liquid 3 to be measured, that is:

[0134] l=kV

[0135] Wherein, k is a proportional coefficient, which can be obtained through calibration; therefore, after determining the output voltage of the bridge, the liquid level height l of the liquid to be measured 3 can be determined.

[0136] Reference Figure 9 In the fifth embodiment of the present application, another configuration of a liquid level measurement device based on a temperature difference dividing point is provided, which includes:

[0137] A slender structural member 1 for partially inserting into the liquid to be tested, wherein a heat-conducting liquid 11 is injected into the inner cavity of the slender structural member, and the whole has a small thermal inertia;

[0138] A control device 2, a heating wire 21 connected to the control device 2 by a wire passes through the elongated structural member 1 and is immersed in the heat-conducting liquid 11;

[0139] Infrared blocking rings 4, a plurality of infrared blocking rings 4 are evenly spaced and mounted on the outside of the elongated structural member 1, with the spacing between the blocking rings corresponding to the number of imaging pixels of the infrared thermographic imaging device in millimeters;

[0140] An infrared thermographic imaging device 5 is provided outside the liquid to be measured 3, and it collects infrared images toward the slender structural member 1. The liquid level of the liquid to be measured 3 is obtained by determining the position of the liquid level temperature dividing line based on the infrared image collected by the infrared thermographic imaging device 5 and in combination with the shielding ring.

[0141] The heating wire inside the elongated structural member 1 heats the heat-conducting liquid 11, raising its temperature. The elongated structural member 1 then acts as a light source, emitting infrared light. When the elongated structural member 1 is inserted into the test liquid 3, the heat exchange between the test liquid 3 and the heat-conducting liquid 11 forms a temperature boundary line within the elongated structural member 1. Because the heat capacity and thermal conductivity of the test liquid 3 differ from those of the heat-conducting liquid 11, the position of the temperature boundary line changes with changes in the liquid level.

[0142] Using an infrared thermographic device to capture a thermal image of the surface of the elongated structural member 1, a clear contrast is formed in the thermal image due to the temperature difference between the temperature boundary and the surrounding area. By controlling the pan / tilt rotation angle, the camera of the infrared thermographic device 5 can be positioned to the section of the elongated structural member where the image is located, and a clear image of that section can be obtained.

[0143] By adjusting the camera of the infrared thermographic device 5 so that it sequentially captures infrared images of the heat-conducting liquid 11 between the two infrared shielding rings 4 from top to bottom, the resulting infrared image clearly displays the liquid level-temperature boundary. Once this liquid level-temperature boundary is determined, the liquid level of the liquid 3 to be measured can be quickly confirmed. For example, if the elongated structural member 1 is evenly divided into 10 segments, each representing 10% of the liquid level height, then if the temperature boundary is located in the third segment from top to bottom, the height of the liquid level boundary in the third segment is first determined. The resulting height of the liquid level boundary is then added to the heights of the remaining seven segments to obtain the liquid level of the liquid 3 to be measured.

[0144] The liquid level measurement method in the fifth embodiment does not depend on light conditions, and therefore can maintain stable liquid level measurement performance in any lighting environment. Furthermore, the liquid level measurement device does not require human manipulation; it only requires placing the slender structural member 1 in the liquid to be measured to achieve automatic liquid level measurement. It is particularly suitable for environments that are not suitable for human manipulation, such as rivers, urban water supply, and drainage pipes. Furthermore, since the heating wire 21 is disposed inside the slender structural member 1, it will not be directly exposed to the liquid 3 to be measured, and the infrared thermographic imaging device 5 is disposed above the liquid surface, interference in the liquid 3 to be measured will not affect the operation of the device inside the slender structural member 1. Therefore, the liquid level measurement device has good anti-interference capabilities.

[0145] The liquid level measuring device in the aforementioned embodiments of the present application can be used for liquid level measurement in water bodies such as rivers, urban water supply, drainage pipes, various pools, water tanks, as well as storage tanks and oil tanks in the oil, natural gas, food and other industries that are not suitable for human operation. It has good anti-interference ability and can work in dark environments.

[0146] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other.

[0147] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0148] It should also be noted that, in this document, the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are for the purpose of facilitating the description of the present invention and simplifying the description, rather than indicating or implying that the devices or components referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention. In addition, relational terms such as "first" and "second" are used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any actual relationship or order between these entities or operations, nor should they be understood as indicating or implying relative importance. Moreover, the terms "comprises", "includes" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device comprising a series of elements does not include those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or terminal device comprising the element.

[0149] The technical solutions provided by the present invention have been described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is intended only to facilitate understanding of the present invention, and the contents of this specification should not be construed as limiting the present invention. Furthermore, those skilled in the art will appreciate that various modifications may be made to the specific implementation methods and scope of application according to the present invention. It is not necessary and impossible to exhaustively enumerate all implementation methods herein, and any obvious variations or modifications derived therefrom remain within the scope of protection of the present invention.

Claims

1. A liquid level measuring device based on a temperature difference dividing point, characterized in that: include: a slender structural member (1) for partially inserting into a liquid to be tested (3), wherein a heat-conducting liquid (11) is injected into an inner cavity of the slender structural member (1); A control device (2), a heating wire (21) and a first temperature-sensitive material resistance wire (22) connected to the control device (2) by a wire, pass through the slender structural member (1) and are immersed in the heat-conducting liquid (11), and the ends of the heating wire (21) and the first temperature-sensitive material resistance wire (22) are in contact with the bottom of the inner cavity of the slender structural member (1); a first temperature-sensitive resistor (23) and a second temperature-sensitive resistor (24) connected to the control device (2), wherein the first temperature-sensitive resistor (23) is arranged on the top of the heat-conducting liquid (11), and the second temperature-sensitive resistor (23) is arranged on the bottom of the heat-conducting liquid (11); When performing liquid level measurement, one end of the slender structural member (1) is inserted into the liquid (3) to be measured, and the control device (2) controls the heating wire (21) to heat the heat-conducting liquid (11); after the heat-conducting liquid (11) is heated, the liquid level of the liquid (3) to be measured is determined based on the real-time temperatures detected by the first temperature-sensitive resistor (23) and the second temperature-sensitive resistor (24) respectively, and the measured resistance of the first temperature-sensitive material resistance wire (22).

2. The liquid level measuring device based on the temperature difference dividing point according to claim 1 is characterized in that: The step of determining the liquid level of the liquid (3) to be measured according to the real-time temperatures detected by the first temperature-sensitive resistor (23) and the second temperature-sensitive resistor (24) respectively and the measured resistance of the first temperature-sensitive material resistance wire (22) comprises: According to the formula: Calculating the liquid level l of the liquid to be measured (3); Wherein, R1 is the measured resistance of the first temperature-sensitive material resistance wire (22), R2 is the resistance of the first temperature-sensitive material resistance wire (22) calculated at the temperature measured by the first temperature-sensitive resistor (23), R3 is the resistance of the first temperature-sensitive material resistance wire (22) calculated at the temperature measured by the second temperature-sensitive resistor (24), and L is the length of the first temperature-sensitive material resistance wire (22).

3. The liquid level measuring device based on the temperature difference dividing point according to claim 1, characterized in that: A second temperature-sensitive material resistance wire (25) connected to the control device (2) by a wire is installed at the top end of the elongated structural member (1) and immersed in the heat-conducting liquid (11); The second temperature-sensitive material resistance wire (25) is made of the same material and has the same diameter as the first temperature-sensitive material resistance wire (22); When performing liquid level measurement, one end of the slender structural member (1) is inserted into the liquid (3) to be measured, and the control device (2) controls the heating wire (21) to heat the heat-conducting liquid (11); after the heat-conducting liquid (11) is heated, the liquid level of the liquid (3) to be measured is determined based on the real-time temperature detected by the second temperature-sensitive resistor (24) and the measured resistances of the first temperature-sensitive material resistance wire (22) and the second temperature-sensitive material resistance wire (25).

4. The liquid level measuring device based on the temperature difference dividing point according to claim 3 is characterized in that: The second temperature-sensitive material resistance wire (25) has the same length as the first temperature-sensitive material resistance wire (22), and the step of determining the liquid level of the liquid (3) to be measured based on the real-time temperature detected by the second temperature-sensitive resistor (24) and the measured resistances of the first temperature-sensitive material resistance wire (22) and the second temperature-sensitive material resistance wire (25) comprises: By formula: The liquid level l of the liquid (3) to be measured is calculated, wherein R1 is the measured resistance of the first temperature-sensitive material resistance wire (22), R3 is the resistance of the first temperature-sensitive material resistance wire (22) calculated at the temperature measured by the second temperature-sensitive resistor (24), R4 is the measured resistance of the second temperature-sensitive material resistance wire (25), and L is the length of the first temperature-sensitive material resistance wire (22).

5. The liquid level measuring device based on the temperature difference dividing point according to claim 1 is characterized in that: A second temperature-sensitive material resistance wire (25) connected to the control device (2) by a wire is installed at the top end of the elongated structural member (1) and immersed in the heat-conducting liquid (11); The second temperature-sensitive material resistance wire (25) and the first temperature-sensitive material resistance wire (22) are made of the same material and have the same diameter; A third temperature-sensitive material resistance wire (26) connected to the control device (2) by a wire passes through the slender structural member (1) and is immersed in the heat-conducting liquid (11), and an end of the third temperature-sensitive material resistance wire (26) is arranged at the bottom of the inner cavity of the slender structural member (1); A fourth temperature-sensitive material resistance wire (27) connected to the control device (2) by a wire is installed at the top end of the slender structural member (1) and immersed in the heat-conducting liquid (11); the fourth temperature-sensitive material resistance wire (27) and the first temperature-sensitive material resistance wire (22) are made of the same material and have the same diameter; When performing liquid level measurement, one end of the slender structural member (1) is inserted into the liquid (3) to be measured, and the control device (2) controls the heating wire (21) to heat the heat-conducting liquid (11); after the heat-conducting liquid (11) is heated, the liquid level of the liquid (3) to be measured is determined based on the measured resistances of the first temperature-sensitive material resistance wire (22), the second temperature-sensitive material resistance wire (25), the third temperature-sensitive material resistance wire (26), and the fourth temperature-sensitive material resistance wire (27).

6. The liquid level measuring device based on the temperature difference dividing point according to claim 5, characterized in that: The liquid level of the liquid (3) to be measured is determined based on the measured resistances of the first temperature-sensitive material resistance wire (22), the second temperature-sensitive material resistance wire (25), the third temperature-sensitive material resistance wire (26), and the fourth temperature-sensitive material resistance wire (27): By formula: Determine the output voltage V of the bridge where the first temperature-sensitive material resistance wire (22), the second temperature-sensitive material resistance wire (25), the third temperature-sensitive material resistance wire (26), and the fourth temperature-sensitive material resistance wire (27) are located; wherein R1 is the measured resistance of the first temperature-sensitive material resistance wire (22), R2 is the measured resistance of the second temperature-sensitive material resistance wire (25), R3 is the measured resistance of the third temperature-sensitive material resistance wire (26), R4 is the measured resistance of the fourth temperature-sensitive material resistance wire (27), and U0 is the power supply voltage of the bridge where the first temperature-sensitive material resistance wire (22), the second temperature-sensitive material resistance wire (25), the third temperature-sensitive material resistance wire (26), and the fourth temperature-sensitive material resistance wire (27) are located; By formula: l=kV Calculate the liquid level height l of the liquid to be measured (3); wherein k is a preset proportional coefficient.

7. A liquid level measuring device based on a temperature difference dividing point, characterized in that: include: A slender structural member (1) for partially inserting into a liquid (3) to be tested, wherein a heat-conducting liquid (11) is injected into an inner cavity of the slender structural member (1) and the entire structure has a relatively small thermal inertia; A control device (2), a heating wire (22) connected to the control device (2) by a wire, passing through the elongated structural member (1) and immersed in the heat-conducting liquid (11); Infrared ray blocking rings (4), a plurality of infrared ray blocking rings (4) are evenly spaced and sleeved on the outside of the elongated structural member (1); An infrared thermographic imaging device (5) is disposed outside the liquid to be measured (3), and is directed toward the elongated structural member (1) to collect infrared images. The position of the liquid level temperature boundary line is determined based on the infrared image collected by the infrared thermographic imaging device (5) and in combination with the shielding ring, thereby obtaining the liquid level of the liquid to be measured (3); The spacing between the infrared blocking rings (4) is equivalent to the number of millimeters corresponding to the number of imaging pixels of the infrared thermographic imaging device (5) used.

8. The liquid level measuring device based on temperature difference dividing point according to claim 1, 3, 5 or 7, characterized in that: The heating wire (21) is a silica gel heating wire or a carbon fiber heating wire.

9. The liquid level measuring device based on temperature difference dividing point according to claim 1, 3, 5 or 7, characterized in that: The heat conduction liquid (11) is a fluorinated liquid or transformer oil, and the elongated structural member (1) is a thin-walled stainless steel tube.

10. The liquid level measuring device based on temperature difference dividing point according to claim 5, characterized in that: The first temperature-sensitive material resistance wire (22), the second temperature-sensitive material resistance wire (25), the third temperature-sensitive material resistance wire (26) and the fourth temperature-sensitive material resistance wire (27) are made of materials with a positive temperature coefficient of resistance or a negative temperature coefficient of resistance.

Images