CN215524760U - Liquid level sensor and farmland liquid level detection device - Google Patents

Abstract

The utility model discloses a liquid level sensor and a farmland liquid level detection device, which relate to the technical field of liquid level detection, and the liquid level sensor comprises: the liquid level sensing circuit comprises a plurality of thermosensitive elements which are arranged in series and are arranged at intervals along the vertical direction; and a voltage detection module for detecting a total voltage of the plurality of thermosensitive elements, a first voltage of the top thermosensitive element located at a top end in the vertical direction, and a second voltage of the bottom thermosensitive element located at a bottom end in the vertical direction. The liquid level sensor includes a heat-sensitive element heating module for heating the heat-sensitive element. The liquid level sensor further comprises a control module, and the control module is configured to calculate the number of the heat-sensitive elements below the liquid level of the measured liquid according to a formula and convert the liquid level of the measured liquid according to the number of the heat-sensitive elements below the liquid level. The liquid level sensor and the farmland liquid level detection device are suitable for accurately measuring the farmland liquid level in the complex environment of the farmland.

Description

Liquid level sensor and farmland liquid level detection device

Technical Field

The utility model relates to the technical field of liquid level detection, in particular to a liquid level sensor and a farmland liquid level detection device.

Background

In agricultural production, water quantity is required to be controlled frequently, and crops are controlled by different water levels in different growth stages, so that the quality and the yield of the crops can be improved. For this reason, it is necessary to accurately detect the water level of the farmland to perform drainage and irrigation operations on the farmland.

Disclosure of Invention

The utility model aims to provide a novel liquid level sensor and a farmland liquid level detection device, which are suitable for accurately measuring farmland liquid level in a complex environment of a farmland.

In order to achieve the above object, the present invention provides a liquid level sensor including:

the liquid level sensing circuit comprises a plurality of thermosensitive elements which are arranged in series and are arranged at intervals along the vertical direction; and

and the voltage detection module is used for detecting the total voltage of the plurality of thermosensitive elements, the first voltage of the top thermosensitive element positioned at the top end in the vertical direction and the second voltage of the bottom thermosensitive element positioned at the bottom end in the vertical direction.

Optionally, the liquid level sensor may comprise: and the heat-sensitive element heating module is used for heating the heat-sensitive element.

Optionally, the heat-sensitive element heating module includes a plurality of heating elements provided in one-to-one correspondence with the plurality of heat-sensitive elements.

Alternatively, the heating element and the heat sensitive element may be disposed adjacent; and/or a heat conducting connecting material can be arranged between the heating element and the heat sensitive element.

Optionally, the liquid level sensor may further include:

the outer shell comprises a hollow shell cavity and a liquid passing hole communicated with the hollow shell cavity; and

and the printed circuit board is arranged in the hollow shell cavity, and the plurality of thermosensitive elements are arranged on the printed circuit board.

Alternatively, the thermistor may be a thermistor.

Alternatively, the top thermistor may include a top first end connected to the power input terminal and a top second end connected to the lower adjacent thermistor, the bottom thermistor includes a bottom first end connected to the upper adjacent thermistor and a bottom second end as an output terminal, and the voltage detection module includes:

the first voltage detection device is electrically connected with the first end of the top part;

the second voltage detection device is electrically connected with the second end of the top part;

the third voltage detection device is electrically connected with the first end of the bottom; and

and the fourth voltage detection device is electrically connected with the second end of the bottom.

Optionally, the liquid level sensor may further include:

a control module in communication with the first voltage detection device, the second voltage detection device, the third voltage detection device and the fourth voltage detection device, respectively, the control module being configured to calculate the number n of the heat sensitive elements below the liquid level of the liquid to be measured according to the following formula₂And according to n₂Converting the liquid level of the measured liquid:

n₀＝n₁+n₂；

n₁*(V₁-V₂)+n₂*(V₃-V₄)＝V₁；

wherein n is₀Is the total number of the plurality of thermosensitive elements, n₁Number of above-level heat-sensitive elements above the level of the liquid to be measured, n₂Number of heat-sensitive elements below the level of the liquid to be measured, V₁The voltage value, V, obtained for the first voltage detection means₂For the voltage value, V, obtained by the second voltage detection means₃The voltage value, V, obtained for the third voltage detection means₄Is the voltage value obtained by the fourth voltage detection means.

Optionally, the first voltage detection device, the second voltage detection device, the third voltage detection device, and the fourth voltage detection device may be ADC voltage acquisition devices, respectively.

Correspondingly, this application still provides a farmland liquid level detection device, and this farmland liquid level detection device includes foretell level sensor.

The liquid level sensor comprises a liquid level sensing circuit and a voltage detection module, wherein the liquid level sensing circuit comprises a plurality of thermosensitive elements which are arranged in series at intervals along the vertical direction, and the voltage detection module is used for detecting the total voltage of the plurality of thermosensitive elements, the first voltage of the top thermosensitive element positioned at the top end in the vertical direction and the second voltage of the bottom thermosensitive element positioned at the bottom end in the vertical direction. The voltage of the thermosensitive element positioned outside the liquid can be known by measuring the first voltage of the top thermosensitive element, and the voltage of the thermosensitive element positioned inside the liquid can be known by measuring the second voltage of the bottom thermosensitive element. At this time, the total number of the thermosensitive elements, the voltage of the thermosensitive element positioned outside the liquid, the voltage of the thermosensitive element positioned inside the liquid and the total voltage of the plurality of thermosensitive elements are known, so that the number of the thermosensitive elements below the liquid level can be calculated according to the voltage rule of the series circuit, and the liquid level can be judged according to the number of the thermosensitive elements below the liquid level. The liquid level measurement process of the liquid level sensor is not influenced by the quality of the farmland water, and the liquid level of the farmland can be accurately measured in the complex environment of the farmland so as to realize the monitoring of the irrigation and water conservancy.

Additional features and advantages of the utility model will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the utility model and are incorporated in and constitute a part of this specification, illustrate embodiments of the utility model and together with the description serve to explain the principles of the utility model and not to limit the utility model. In the drawings:

FIG. 1 illustrates a schematic structural diagram of a fluid level sensor in accordance with an embodiment of the present invention;

FIG. 2 is a schematic diagram of the printed circuit board of FIG. 1;

FIG. 3 is a schematic connection diagram of a level sensing circuit of the level sensor of FIG. 1; and

FIG. 4 is a schematic diagram of the connection of the fluid level sensing circuit of the fluid level sensor of FIG. 1 to the thermistor heating module.

Description of the reference numerals

100 liquid level sensor

1 Heat-sensitive element 11 Top Heat-sensitive element

12 bottom thermosensitive element 13 middle thermosensitive element

2 heating element

3 hollow shell cavity of outer shell 31

32-liquid-passing hole 4 printed circuit board

51 first voltage detection means 52 second voltage detection means

53 third voltage detection means 54 fourth voltage detection means

6 control module 7 power supply

Detailed Description

The following detailed description of specific embodiments of the utility model refers to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and explanatory of the utility model and are not restrictive thereof.

The liquid level sensor 100 according to the present invention will be described below with reference to the accompanying drawings, which the liquid level sensor 100 can accurately measure the liquid level of the agricultural field in the complicated environment of the agricultural field.

The existing liquid level sensor mainly adopts a floating ball type, a capacitance type, a static pressure type, a distance measurement type and the like. The floating ball type liquid level measurement device measures liquid level by utilizing the change of magnetic inductors at different positions caused by the change of water level, and the floating ball is easily influenced by impurities in liquid because the floating ball needs to move along with the change of the liquid level, so that the floating ball type liquid level measurement device is applied to the environments such as farmlands and the like, and needs to well protect the surrounding environment of the floating ball. The capacitance type measurement mainly measures the material level height by detecting the capacitance value change caused by the height change of the liquid level or the bulk cargo, the dielectric constant of the liquid needs to be detected, a minimum measurement range blind area exists, in the complex environments such as farmlands, water with soil and water layers without soil have the effect of soil, the dielectric constant difference is large, the detection cannot be accurately performed, and therefore the capacitance type measurement is not suitable for the liquid level detection with the layering characteristic. The static pressure type is that a pressure sensor arranged at the bottom is utilized, the liquid level height is calculated through conversion by detecting the liquid pressure at the bottom, the reference value of the liquid pressure at the bottom is the atmospheric pressure or the known air pressure communicated with the top, the detection mode requires the adoption of a high-precision and flush type pressure sensor, and meanwhile, the conversion process needs to be continuously calibrated. The distance measurement method is to measure the distance from the emitter to the liquid level by using the principle that laser, ultrasonic wave or microwave is reflected when entering the liquid level from the air, so as to calculate the height of the liquid level, but the distance measurement method is easily shielded by foreign objects, such as plants, and the like, and additional environmental protection is needed.

Due to the farmland water quality in different periods, the ion density difference in water is large, even turbid water quality mixed with water and mud can occur, and therefore the accurate measurement of the liquid level is influenced. In view of the above, the inventor of the present application provides a liquid level sensor 100 suitable for accurately measuring the liquid level of an agricultural field in the complex environment of the agricultural field so as to realize the monitoring of the irrigation and water conservancy.

The liquid level sensor comprises a liquid level sensing circuit and a voltage detection module, wherein the liquid level sensing circuit comprises a plurality of thermosensitive elements 1 which are arranged in series and are arranged at intervals along the vertical direction, and the voltage detection module is used for detecting the total voltage of the plurality of thermosensitive elements 1, the first voltage of a top thermosensitive element 11 positioned at the top end in the vertical direction and the second voltage of a bottom thermosensitive element 12 positioned at the bottom end in the vertical direction. Here, the voltage of the thermistor 1 located outside the liquid can be known by measuring the first voltage of the top thermistor 11, and the voltage of the thermistor 1 located inside the liquid can be known by measuring the second voltage of the bottom thermistor 12. At this time, the total number of the thermosensitive elements 1, the voltage of the thermosensitive element 1 located outside the liquid, the voltage of the thermosensitive element 1 located inside the liquid, and the total voltage of the plurality of thermosensitive elements 1 are known, so that the number of the thermosensitive elements 1 below the liquid surface can be calculated according to the voltage rule of the series circuit, and the liquid level can be determined according to the number of the thermosensitive elements 1 below the liquid surface. This level sensor 100's liquid level measurement process does not receive the influence of farmland quality of water, can accurately measure the monitoring of farmland liquid level in order to realize irrigation and water conservancy in the complex environment in farmland.

Referring to fig. 1 to 4, the plurality of thermosensitive elements 1 arranged at intervals in the vertical direction include a top thermosensitive element 11 located at the top end in the vertical direction, a bottom thermosensitive element 12 located at the bottom end in the vertical direction, and a plurality of middle thermosensitive elements 13 located between the top and bottom thermosensitive elements 11 and 12. When liquid level measurement is needed, at least one thermosensitive element 1 is positioned below the liquid level of the liquid to be measured, at least one thermosensitive element 1 is positioned above the liquid level of the liquid to be measured, namely at least the bottom thermosensitive element 12 is positioned below the liquid level of the liquid to be measured, and at least the top thermosensitive element 11 is positioned above the liquid level of the liquid to be measured. Wherein the number n of the heat sensitive elements below the liquid level of the liquid to be measured is calculated according to the following formula₂And according to n₂Converting the liquid level of the measured liquid:

n₀＝n₁+n₂；

n₁*V_{on the liquid level}+n₂*V_{Under the liquid level}＝V_{General assembly}。

n₀Is the total number of the plurality of heat sensitive elements 1, n₁Number of above-level heat-sensitive elements above the level of the liquid to be measured, n₂The number of the thermosensitive elements below the liquid level of the measured liquid is the number of the thermosensitive elements below the liquid level; v_{On the liquid level}As a roof at the top end in the vertical directionA first voltage, V, of the thermistor 11_{Under the liquid level}Second voltage, V, of the bottom thermo-sensitive element 12 at the bottom end in the vertical direction_{General assembly}Is the total voltage of the plurality of heat sensitive elements 1.

It should be noted that the specifications of the plurality of thermosensitive elements 1 may be the same, and thus, the voltage of the thermosensitive element 1 located outside the liquid may be approximately regarded as the voltage of the top thermosensitive element 11, and the voltage of the thermosensitive element 1 located inside the liquid may be approximately regarded as the voltage of the bottom thermosensitive element 12, which may further simplify the operation process. Of course, the present application is not limited thereto, and the specifications of the plurality of thermosensitive elements 1 may be different, and in this case, the offset compensation may be added during the calculation process to achieve the function. When the number of the thermosensitive elements 1 below the liquid surface is calculated as a non-integer, the number of the thermosensitive elements 1 below the liquid surface may be an integer closest to the calculation result.

Optionally, the thermistor 1 is a thermistor with high sensitivity, and when the thermistor is immersed under liquid, the thermistor dissipates heat quickly and the temperature rises slowly; when the thermistor is positioned above the liquid level, the heat dissipation rate is relatively slow, the temperature rises quickly by depending on air for heat dissipation, and at the moment, the thermosensitive elements 1 positioned inside and outside the liquid can show obvious resistance difference, so that the number of the thermosensitive elements 1 below the liquid level can be calculated by measuring the voltage and the total voltage of the two.

Because the resistance values of some thermal sensitive elements are generally small, in order to enable the thermal sensitive elements 1 above and below the liquid level to present resistance values with large difference, a power supply 7 with large voltage or current is generally required to be connected into the liquid level sensing circuit, and the power supply 7 outputs voltage or current for the liquid level sensing circuit. In order to reduce the configuration cost of the power supply 7 and further enable the thermal sensitive elements 1 above and below the liquid level to have different resistance values, the liquid level sensor 100 may further include a thermal sensitive element heating module for heating the thermal sensitive elements 1, so that the cost can be effectively saved and the detection performance of the liquid level sensor 100 can be improved.

Alternatively, the heat-sensitive element heating module may include a plurality of heating elements 2 provided in one-to-one correspondence with the plurality of heat-sensitive elements 1. The heating element 2 may be a heating resistor, which is low in cost and easy to obtain. As shown in fig. 4, the heat-sensitive element heating module may be a heating circuit independent from the liquid level sensing circuit, and a plurality of heating elements 2 are arranged in series in the heating circuit and arranged in one-to-one correspondence with the plurality of heat-sensitive elements 1. Of course, a plurality of heating elements 2 can also be arranged in parallel; alternatively, the heat-sensitive element heating module may be in other forms of heating structures, such as a monolithic heating plate or heating rod, and the application is not limited thereto.

Further, in order to improve the heat transfer efficiency of the heating element 2 to the heat sensitive element 1, the heating element 2 and the heat sensitive element 1 may be disposed adjacent to each other in one-to-one correspondence. Further, in order to allow sufficient heat exchange between the heating element 2 and the heat sensitive element 1, a heat conductive connecting material may be provided between the heating element 2 and the heat sensitive element 1.

Alternatively, as shown in fig. 1, the liquid level sensor 100 may further include an outer housing 3, the outer housing 3 includes a hollow housing cavity 31 and a liquid passing hole 32 communicating with the hollow housing cavity 31, the plurality of thermal sensitive elements 1 are disposed in the hollow housing cavity 31, and the liquid passing hole 32 may ensure that liquid enters the hollow housing cavity 32 from outside the outer housing 3 and contacts the corresponding thermal sensitive element 1. In addition, the liquid level sensor 100 may further include a printed circuit board 4, the printed circuit board 4 being provided in the hollow housing chamber 31, the plurality of thermosensors 1 being mounted on the printed circuit board 4. As shown in fig. 2, a plurality of thermosensitive elements 1 are arranged at intervals in the vertical direction on a printed circuit board 4. The liquid passing hole 32 may include a plurality of holes disposed at different height positions, so that the liquid of the outer shell 3 can be more smoothly and timely introduced into the hollow shell cavity 31 for heat exchange. The shapes of the outer casing 3, the liquid passing hole 32, and the printed circuit board 4 may be various, but the present application is not limited thereto.

In some embodiments, as shown in fig. 3 and 4, the top thermo-element 11 may include a top first end and a top second end as electrical connection terminals, the top first end of the top thermo-element 11 is connected with the power input terminal of the power supply 7, and the top second end of the top thermo-element 11 is connected with the middle thermo-element 13 adjacent below. The bottom thermo-element 12 may include a bottom first end connected to the upper adjacent middle thermo-element 13 and a bottom second end as an electrical connection end, the bottom second end being an output end. The voltage detection module may include a first voltage detection device 51, a second voltage detection device 52, a third voltage detection device 53 and a fourth voltage detection device 54. The first voltage detection device 51 is electrically connected to the top first terminal, the second voltage detection device 52 is electrically connected to the top second terminal, the third voltage detection device 53 is electrically connected to the bottom first terminal, and the fourth voltage detection device 54 is electrically connected to the bottom second terminal. As such, the total voltage of the plurality of thermosensors 1 may be the voltage acquired by the first voltage detecting means 51, the first voltage of the top thermosensor 11 may be the voltage difference acquired by the first voltage detecting means 51 and the second voltage detecting means 52, and the second voltage of the bottom thermosensor 12 may be the voltage difference acquired by the third voltage detecting means 53 and the fourth voltage detecting means 54. At this time, the number of the thermosensitive elements 1 below the liquid level can be calculated according to the voltage rule of the series circuit, and the liquid level can be further judged according to the number of the thermosensitive elements 1 below the liquid level.

Further, the liquid level sensor 100 further comprises a control module 6, and the control module 6 is in communication with the first voltage detection device 51, the second voltage detection device 52, the third voltage detection device 53 and the fourth voltage detection device 54, respectively. The control module 6 may be configured to calculate the number n of thermo-sensitive elements below the level of the measured liquid according to the following formula₂And according to n₂Converting the liquid level of the measured liquid:

n₀＝n₁+n₂；

n₁*(V₁-V₂)+n₂*(V₃-V₄)＝V₁。

wherein n is₀Is the total number of the plurality of heat sensitive elements 1, n₁Number of above-level heat-sensitive elements above the level of the liquid to be measured, n₂The number of the thermosensitive elements below the liquid level of the measured liquid is as follows: n is₀＝n₁+n₂；

V₁For the voltage value, V, obtained by the first voltage detection means 51₂For the second voltage detecting means 52Taken voltage value, V₃For the voltage value, V, obtained by the third voltage detecting means 53₄Is the voltage value acquired by the fourth voltage detection means 54. The total voltage of the plurality of heat sensitive elements 1 is V₁The first voltage of the top thermistor 11 is V₁－V₂The second voltage of the bottom thermistor 12 is V₃－V₄. According to the voltage law of the series circuit, n is known₁*(V₁-V₂)+n₂*(V₃-V₄)＝V₁。

Since n is₀Is a known value, so n can be set₁＝n₀-n₂Substitution into

n₁*(V₁-V₂)+n₂*(V₃-V₄)＝V₁In (1),

i.e. by (n)₀-n₂)*(V₁-V₂)+n₂*(V₃-V₄)＝V₁Can calculate n₂. And, in the case of finding n₂And then, the corresponding liquid level of the measured liquid can be converted through a preset conversion rule in the control module 6.

It should be noted that, the specifications of the plurality of thermosensitive elements 1 applied in the above calculation formula are the same, so that the calculation process can be further simplified. Of course, the present application is not limited thereto, and the specifications of the plurality of thermosensitive elements 1 may be different, and in this case, the offset compensation may be added to the formula to achieve the function. The lower liquid level thermosensitive element is a thermosensitive element 1 below the liquid level of the liquid to be measured, and the upper liquid level thermosensitive element is a thermosensitive element 1 above the liquid level of the liquid to be measured.

The voltage detection devices of the voltage detection module may be various, and optionally, the first voltage detection device 51, the second voltage detection device 52, the third voltage detection device 53 and the fourth voltage detection device 54 may be ADC voltage acquisition devices known to those skilled in the art respectively.

The liquid level sensor 100 of the present application can be applied to the measurement of liquid level in a complex natural environment, for example, in a farmland in a complex natural environment, because it is not affected by the environment such as water quality, impurities, etc. Therefore, the application also provides a farmland liquid level detection device which comprises the liquid level sensor and can be applied to farmland liquid level measurement in a complex natural environment.

In conclusion, the utility model provides the liquid level sensor 100 and the farmland liquid level detection device, the liquid level measurement process of the liquid level sensor 100 and the farmland liquid level detection device is not influenced by the water quality of the farmland, and the farmland liquid level can be accurately measured in the complex environment of the farmland so as to realize the monitoring of the irrigation and water conservancy.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the utility model and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the utility model.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; may be mechanically coupled, may be electrically coupled or may be in communication with each other; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims (9)

1. A liquid level sensor, characterized in that the liquid level sensor (100) comprises:

the liquid level sensing circuit comprises a plurality of thermosensitive elements (1) which are arranged in series and are arranged at intervals along the vertical direction; and

and the voltage detection module is used for detecting the total voltage of the plurality of thermosensitive elements (1), the first voltage of the top thermosensitive element (11) positioned at the top end in the vertical direction and the second voltage of the bottom thermosensitive element (12) positioned at the bottom end in the vertical direction.

2. The fluid level sensor according to claim 1, wherein the fluid level sensor (100) further comprises: the heat-sensitive element heating module is used for heating the heat-sensitive element (1).

3. The liquid level sensor according to claim 2, wherein the heat-sensitive element heating module comprises a plurality of heating elements (2) provided in one-to-one correspondence with a plurality of the heat-sensitive elements (1).

4. A liquid level sensor according to claim 3, characterised in that the heating element (2) is arranged adjacent to the heat sensitive element (1); and/or a heat-conducting connecting material is arranged between the heating element (2) and the thermosensitive element (1).

5. The fluid level sensor according to claim 1, wherein the fluid level sensor (100) further comprises:

the outer shell (3) comprises a hollow shell cavity (31) and a liquid passing hole (32) communicated with the hollow shell cavity (31); and

the printed circuit board (4) is arranged in the hollow shell cavity (31), and the thermosensitive elements (1) are arranged on the printed circuit board (4).

6. The level sensor according to claim 1, characterized in that the thermally sensitive element (1) is a thermistor.

7. The level sensor according to any one of claims 1 to 6, wherein the top thermistor (11) comprises a top first end connected to a power input and a top second end connected to the thermistor (1) adjacent below, the bottom thermistor (12) comprises a bottom first end connected to the thermistor (1) adjacent above and a bottom second end as an output, and the voltage detection module comprises:

a first voltage detection device (51) electrically connected to the top first end;

a second voltage detection device (52) electrically connected to the top second end;

a third voltage detection device (53) electrically connected to the first end of the bottom portion; and

and the fourth voltage detection device (54) is electrically connected with the second end of the bottom.

8. The liquid level sensor according to claim 7, wherein the first voltage detection means (51), the second voltage detection means (52), the third voltage detection means (53) and the fourth voltage detection means (54) are ADC voltage acquisition means, respectively.

9. An agricultural field liquid level detection device, characterized in that it comprises a liquid level sensor according to any one of claims 1 to 8.

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