CN113252136A

CN113252136A - Liquid level sensor

Info

Publication number: CN113252136A
Application number: CN202110519341.XA
Authority: CN
Inventors: 朱军
Original assignee: Beijing Bld Measurement & Control Instrument Co ltd
Current assignee: Beijing Bld Measurement & Control Instrument Co ltd
Priority date: 2021-05-12
Filing date: 2021-05-12
Publication date: 2021-08-13

Abstract

The application relates to a liquid level sensor, which comprises a measuring sensor, a unit sensor and a connecting piece, wherein the measuring sensor and the unit sensor are arranged on the same side of the connection; the measuring sensor is used for measuring capacitance when a medium is contained, the unit sensor is used for measuring capacitance when a certain volume of medium is contained, and the respective terminals of the measuring sensor and the unit sensor penetrate through the connecting piece. When the liquid level sensor is placed in a medium to be measured, the depth of the medium to be measured in the measuring sensor is the depth to be measured, and the depth of the medium to be measured in the unit sensor is the fixed depth. Through the wiring end of connecting measurement sensor and the wiring end of cell sensor, can obtain two capacitance values, combine two capacitance values and fixed depth value can obtain the degree of depth that awaits measuring to obtain comparatively accurate liquid level height value, and then improved the accuracy of measuring result.

Description

Liquid level sensor

Technical Field

The application relates to the field of detection equipment, in particular to a liquid level sensor.

Background

The liquid level sensor is a detection device for detecting the liquid level height, and most of common liquid level sensors are manufactured based on the principles of fluid statics, electromagnetic effect, dielectric constant, buoyancy, waveform reflection and the like.

Each type of level sensor has its scope of applicability and certain limitations. For example, for the measurement of the level of liquefied natural gas. Since the liquefied natural gas has a certain volatility, when the liquid level is measured, the liquid level is usually measured directly by a liquid level sensor.

However, because the measurement environment of the lng is poor, the accuracy of the measurement result is not high when the existing level sensor measures the level of the lng.

Disclosure of Invention

In order to improve the accuracy of the measurement results, the present application provides a liquid level sensor.

The application provides a level sensor adopts following technical scheme:

a liquid level sensor comprises a measuring sensor, a unit sensor and a connecting piece, wherein the measuring sensor and the unit sensor are arranged on the same side of the connection, the end parts of the measuring sensor and the unit sensor, which are far away from respective openings, are connected with the connecting piece, and the edges of the two openings are flush;

the measuring sensor is used for measuring capacitance when a medium is contained, the unit sensor is used for measuring capacitance when a certain volume of medium is contained, and the terminals of the measuring sensor and the unit sensor penetrate through the connecting piece.

Through adopting above-mentioned technical scheme, when the level sensor of this application was placed in the medium that awaits measuring, the degree of depth of the medium that awaits measuring in the measuring sensor was the degree of depth that awaits measuring, and the degree of depth of the medium that awaits measuring in the unit sensor is fixed degree of depth. Through the wiring end of connecting the measuring sensor, can obtain the electric capacity between the measuring sensor wiring end, through the wiring end of connecting the unit sensor, can obtain the electric capacity between the unit sensor wiring end, combine two capacitance value and fixed depth value can obtain the depth of awaiting measuring to obtain comparatively accurate liquid level height value, and then improved measuring result's accuracy.

Optionally, the measuring sensor includes a first electrode rod, a first inner sleeve and an outer sleeve, the first inner sleeve and the outer sleeve are coaxially arranged, a certain gap exists between the first inner sleeve and the outer sleeve, the first electrode rod is arranged on the axis of the first inner sleeve and the axis of the outer sleeve, and a fixing plate is arranged between the first electrode rod and the first inner sleeve.

Through adopting above-mentioned technical scheme, first inner skleeve and first electrode bar can be fixed to the fixed plate for first inner skleeve and first electrode bar relatively fixed. When the measuring sensor is placed in a medium to be measured, the terminal connected with the first inner sleeve or the outer sleeve and the terminal of the first electrode rod can detect the capacitance of the conductive medium; connecting the terminal of the first inner sleeve and the terminal of the outer sleeve enables the capacitance of the non-conductive medium to be detected.

Optionally, one end of the outer sleeve is fixedly arranged on the connecting piece, and a plurality of fixing blocks are arranged between the first inner sleeve and the outer sleeve.

Through adopting above-mentioned technical scheme, a plurality of fixed blocks make and can have certain distance between outer sleeve and the first inner skleeve.

Optionally, the fixing plate is provided with a plurality of liquid passing holes.

By adopting the technical scheme, the liquid passing hole can allow a medium to be measured to enter the measuring sensor.

Optionally, the unit sensor comprises a second electrode rod, a support and a second inner sleeve with the same diameter and length as the first inner sleeve;

the second inner sleeve is fixedly arranged on the connecting piece, a partition is arranged in the second inner sleeve, a preset distance exists between the partition and an opening of the second inner sleeve, the second inner sleeve is divided into a connecting part and a measuring part by the partition, the measuring part is close to the opening of the second inner sleeve, the second electrode rod is arranged on the axis of the second inner sleeve, and the second electrode rod penetrates through the partition and is connected with the partition in a sealing manner;

the supporting piece is arranged outside the second inner sleeve.

By adopting the technical scheme, the measuring part is used for measuring the capacitance of the medium to be measured with the known depth, the second inner sleeve is the same as the first inner sleeve in length, and the second inner sleeve is connected with the measuring part and the connecting piece, so that the edge of the measuring part is flush with the open edge of the first inner sleeve.

Optionally, the supporting piece is cylindrical, a step is formed in one end of the supporting piece along the inner wall, and the end where the step is located is close to the opening of the second inner sleeve.

By adopting the technical scheme, the conductive medium and the non-conductive medium can be respectively measured by connecting different terminals.

Optionally, a distance between the step and the opening of the second inner sleeve is the same as the preset distance, and a width of the step in the circumferential direction of the second inner sleeve is the same as a distance between the outer sleeve and the first inner sleeve.

Through adopting above-mentioned technical scheme, when measuring a certain medium for the data that measuring transducer and unit sensor measured can correspond, in order to obtain comparatively accurate liquid level height result.

Optionally, the step is provided with an air duct, and the air duct communicates the step and the end of the support member far away from the opening of the second inner sleeve.

Through adopting above-mentioned technical scheme, the air duct can be supplied gas outgoing to the medium that awaits measuring gets into the clearance between measuring part and support piece and the second inner skleeve.

Optionally, a side of the partition plate facing the measuring portion is provided with a branch vent. The air passage branch passage communicates the measurement portion with the air passage.

Through adopting above-mentioned technical scheme, the gas escape that the branch of ventilating can supply the measuring part to in the medium that awaits measuring gets into the measuring part.

Optionally, the plurality of fixing blocks are disposed near ends of the first inner sleeve and the outer sleeve.

By adopting the technical scheme, the measuring error caused by the fixed block can be reduced.

In summary, the present application includes at least one of the following beneficial technical effects:

1. when the liquid level sensor is placed in a medium to be measured, the depth of the medium to be measured in the measuring sensor is the depth to be measured, and the depth of the medium to be measured in the unit sensor is the fixed depth. The capacitance between the wiring ends of the measuring sensors can be obtained by connecting the wiring ends of the measuring sensors, the capacitance between the wiring ends of the unit sensors can be obtained by connecting the wiring ends of the unit sensors, and the depth to be measured can be obtained by combining two capacitance values and a fixed depth value so as to obtain a more accurate liquid level height value, thereby improving the accuracy of the measuring result;

2. the provision of the outer sleeve, the first inner sleeve, the first electrode rod, the support, the second inner sleeve and the second electrode rod enables the measuring sensor and the cell sensor to measure the capacitance of the conductive medium and the non-conductive medium, respectively.

Drawings

FIG. 1 is a schematic diagram of a fluid level sensor according to an embodiment of the present application.

Fig. 2 is a partially enlarged view of a portion a in fig. 1.

Fig. 3 is a partially enlarged view at B in fig. 1.

Fig. 4 is a partially enlarged view at C in fig. 1.

Description of reference numerals: 1. a measurement sensor; 11. a first electrode rod; 12. a first inner sleeve; 13. an outer sleeve; 2. a cell sensor; 21. a second electrode bar; 22. a support member; 221. an air duct; 222. an airway branch; 23. a second inner sleeve; 231. a connecting portion; 232. a measuring section; 3. a connecting member; 4. a fixed block; 5. a right-angle type hoop; 6. a terminal; 7. a fixing plate; 71. a liquid passing hole; 8. a partition plate; 9. and (4) a step.

Detailed Description

The present application is described in further detail below with reference to figures 1-4.

The embodiment of the application discloses a liquid level sensor for measure the medium of the liquid level of being not convenient for measure such as liquefied natural gas, in order to obtain comparatively accurate measuring result.

Referring to fig. 1, the liquid level sensor includes a measurement sensor 1, a unit sensor 2, and a connection member 3. Measuring transducer 1 and unit sensor 2 all set up in same one side of connecting piece 3, and measuring transducer 1 keeps away from separately open tip with unit sensor 2 and is connected with connecting piece 3, and two uncovered edges remain and flush to measure the capacitance value of the medium that awaits measuring, specifically include the capacitance value of the medium that awaits measuring under the certain degree of depth and the capacitance value of the medium that awaits measuring under the degree of depth that awaits measuring, and obtain the degree of depth of the medium that awaits measuring through ratio algorithm and known degree of depth.

Referring to fig. 1 and 2, the measuring sensor 1 comprises a first electrode rod 11, a first inner sleeve 12 and an outer sleeve 13, wherein the first inner sleeve 12 and the outer sleeve 13 are two cylinders coaxially arranged. The first inner sleeve 12 and the outer sleeve 13 are placed upright, and a plurality of fixing blocks 4 are arranged between the two sleeves to maintain the stability of the gap between the outer sleeve 13 and the first inner sleeve 12, so that a space for accommodating a medium to be measured exists between the first inner sleeve 12 and the outer sleeve 13. One end of the outer sleeve 13 is fixedly arranged on the connecting piece 3 and can be connected by a fixed connection mode such as bolt connection. Specifically, a clamp is fixedly arranged on the outer sleeve 13, the clamp can be a right-angle clamp 5, a right-angle edge of the right-angle clamp 5 is fixedly connected with the outer sleeve 13, and the other right-angle edge of the right-angle clamp is fixed on the connecting piece 3 through a bolt. To increase the strength of the connection, two right angle clamps 5 are provided, symmetrically arranged about the axis of the first inner sleeve 12 and the outer sleeve 13.

It will be appreciated that the plurality of securing blocks 4 form an interference fit with the first inner sleeve 12 to secure the first inner sleeve 12 to the outer sleeve 13. Of course, the connection can also be performed by a common fixing connection manner such as bonding. In addition, the plurality of fixing blocks 4 are uniformly distributed in the gap between the first inner sleeve 12 and the outer sleeve 13 in the circumferential direction, so that the first inner sleeve 12 can be uniformly stressed in all directions to maintain a coaxial positional relationship with the outer sleeve 13.

Referring to fig. 1, a first electrode rod 11 is disposed at an axial position of a first inner sleeve 12 and an outer sleeve 13, and one end thereof is inserted into the connecting member 3 and protrudes from the connecting member 3 by a certain distance for receiving the terminal 6 for measurement; the other end of which is secured in the first inner sleeve 12 by means of the securing plate 7.

Referring to fig. 1 and 3, in particular, the fixing plate 7 is in a ring shape and is fixedly disposed in the first inner sleeve 12, and is located at an edge of the first inner sleeve 12 near the opening, and can be in interference fit with the first inner sleeve 12, or can be fixed by means of bonding or the like. It can be understood that, when the measurement sensor 1 is placed into the medium to be measured, the medium to be measured enters the measurement sensor 1 from the opening of the measurement sensor 1, so that the fixing plate 7 is provided with a plurality of liquid passing holes 71 along the axial direction of the first inner sleeve 12, and the liquid passing holes 71 may be in a shape such as a circle, a bar, or a rectangle, which facilitates the medium to be measured to flow into the measurement sensor 1.

Referring to figures 1 and 2, of course, the terminals 6 are also provided on the first inner sleeve 12 and the outer sleeve 13, and the terminals 6 on both the first inner sleeve 12 and the outer sleeve 13 pass through the connector 3 and protrude from the connector 3. It is worth mentioning that the different terminals 6 of the measuring sensor 1 are connected to a reading display meter, which measures the capacitance that the measuring sensor 1 is capable of measuring.

Referring to fig. 1, the unit sensor 2 includes a second electrode rod 21, a support 22, and a second inner sleeve 23, wherein the second inner sleeve 23 has the same diameter as the first inner sleeve 12 to form the same measurement environment as the measurement sensor 1, thereby facilitating obtaining a measurement result corresponding to the measurement result of the measurement sensor 1. The second inner sleeve 23 is placed upright and has one end fixedly arranged on the connecting piece 3, which can also be done by means of a fixed connection, such as a bolt connection.

Referring to fig. 1 and 2, in particular, a right angle clamp 5 is fixedly arranged on the second inner sleeve 23 in the same way as the outer sleeve 13. One right-angle side of the right-angle clamp 5 is connected with the second inner sleeve 23, and the other right-angle side is fixed on the connecting piece 3 through a bolt. To increase the strength of the connection, two right-angle clamps 5 are provided, symmetrically arranged about the axis of the second inner sleeve 23. The second electrode bar 21 is arranged on the axis position of the second inner sleeve 23, one end of the second electrode bar is inserted into the connecting piece 3 and extends out of the connecting piece 3 for a certain distance so as to be connected with the terminal 6 for measurement; the other end of which is fixed in the second inner sleeve 23 by means of a partition 8.

Referring to fig. 1, specifically, the partition 8 is in a ring shape and is fixedly disposed in the second inner sleeve 23 and located in the second inner sleeve 23 near the opening, so that a preset distance exists between the partition 8 and the opening of the second inner sleeve 23 to divide the second inner sleeve 23 into a connecting portion 231 and a measuring portion 232, wherein the measuring portion 232 is closer to the opening of the second inner sleeve 23. The connecting portion 231 is used to connect the measuring portion 232 so that the open edge of the second inner sleeve 23 is flush with the open edge of the measuring sensor 1. Since the unit sensor 2 is used for detecting the capacitance of the medium to be measured with a known depth, the second electrode rod 21 penetrates through the partition plate 8 and is hermetically connected with the partition plate 8, and the partition plate 8 and the second inner sleeve 23 are also hermetically connected, and fixing means such as adhesion can be adopted.

The support 22 is arranged outside the second inner sleeve 23. Specifically, the supporting member 22 is cylindrical, and the inner wall thereof is fitted to the outer wall of the second inner sleeve 23. The support 22 has a step 9 along its inner diameter near the open end of the second inner sleeve 23. The width of the step 9 along the circumference of the second inner sleeve 23 is the same as the distance between the outer sleeve 13 and the first inner sleeve 12 to form the same measuring environment as the measuring sensor 1, thereby facilitating the measurement of the conductive medium and the non-conductive medium respectively; the distance between the step 9 and the plane where the second inner sleeve 23 is open is the same as the preset distance, so that the liquid level of the part of the unit sensor 2 where the medium to be measured is located is the same when the unit sensor 2 is measuring, that is, the liquid level is the preset distance.

Referring to fig. 1 and 4, it should be noted that an air duct 221 is formed in the supporting member 22, and an air branch duct 222 is further formed in the partition plate 8, so that when the medium to be measured enters the measuring portion 232, the atmosphere in the measuring portion 232 can be exhausted from the air duct 221 and the air branch duct 222. Specifically, the air duct 221 extends from the step 9 to the end surface of the support member 22 away from the opening of the second inner sleeve 23, and the air duct 221 communicates with the side of the partition plate 8 facing the measurement portion 232 through the air duct 222. Referring to fig. 4, the present embodiment provides only one arrangement, and the arrangement of the air duct 221 and the air duct branch 222 is not limited to a large extent as long as the atmosphere in the measurement portion 232 can be exhausted.

Referring to fig. 1 and 3, in addition, in the embodiment of the present application, the fixing block 4 is preferably provided with eight adjacent to the ends of the outer sleeve 13 and the first inner sleeve 12, respectively, wherein four fixing blocks 4 are provided adjacent to the openings of the outer sleeve 13 and the first inner sleeve 12. The volume occupied by the four fixed blocks 4 brings errors to the measurement result, and therefore, the installation positions of the four fixed blocks 4 are adjusted to a certain extent: the distance between the face of the four fixing blocks 4 remote from the opening of the outer sleeve 13 and the first inner sleeve 12 and the plane of the edge of the opening is less than a predetermined distance, so that errors can be corrected by the measurement results measured by the unit sensor 2.

Referring to fig. 1, since the unit sensor 2 and the measuring sensor 1 are different only in measuring the capacitance of the medium to be measured having different liquid level heights, the unit sensor 2 is also provided with terminals 6 on the second inner sleeve 23 and the support 22, and the terminals 6 on the second inner sleeve 23 and the support 22 are both passed through the connecting member 3 and protruded from the connecting member 3 to measure the capacitance also when the reading display meter is connected to the different terminals 6 of the unit sensor 2.

It can be understood that, whether the measurement is of a conductive medium or a non-conductive medium, after the connection of the corresponding terminals 6, a measurement result obtained by the measurement sensor 1 and a measurement result of the unit sensor 2 can be obtained, wherein the capacitance measured by the measurement sensor 1 corresponds to the capacitance of the medium to be measured at a certain level, the capacitance measured by the unit sensor 2 corresponds to the capacitance of the medium to be measured at a predetermined distance, the predetermined distance is known, and the level of the medium to be measured can be obtained by calculating the ratio of the product of the capacitance measured by the measurement sensor 1 and the predetermined distance to the capacitance measured by the unit sensor 2.

Of course, to the conductivity of the medium to be measured, the level sensor in this application needs to be set differently before measurement:

when the non-conductive medium is measured, because the medium to be measured is insulated, the outer sleeve 13 and the first inner sleeve 12 are made of bare metal as two poles of the capacitor, namely, a reading display instrument is connected with the terminal 6 of the outer sleeve 13 and the first inner sleeve 12. Considering that the holding environment of the medium to be measured is relatively severe, the medium to be measured is preferably made of stainless steel materials. When the measuring sensor 1 is inserted into the medium to be measured, the medium to be measured in the gap between the outer sleeve 13 and the first inner sleeve 12, the outer sleeve 13 and the first inner sleeve 12 constitute a capacitor, and the capacitance thereof is affected by the area formed in the circumferential direction of the outer sleeve 13 and the first inner sleeve 12, the dielectric constant of the medium to be measured, and the gap between the electrode plates.

Likewise, the second inner sleeve 23 and the support 22 are also made of bare metal as the poles of the capacitor, i.e. the readout indicator is connected to the terminals 6 of the support 22 and the second inner sleeve 23. Since the cell sensor 2 measures only the capacitance of the medium to be measured within a predetermined distance, the portion of the second inner sleeve 23 located in the measuring portion 232, the support 22 and the medium to be measured constitute a capacitor.

When conducting a measurement on a conductive medium, the electrodes of the measuring sensor 1 cannot be made directly of bare metal, since the medium to be measured is conductive. For this purpose, one of the outer sleeve 13 or the first inner sleeve 12 and the first electrode rod 11 serve as two poles of a capacitor, wherein the first electrode rod 11 is a metal rod coated with an extremely thin and dielectric constant stable insulating layer, preferably teflon, and the outer sleeve 13 or the first inner sleeve 12 is still made of bare metal. In the present embodiment the reading display instrument is preferably connected to the outer sleeve 13 and the terminal 6 of the first electrode rod 11.

It can be understood that, the measuring sensor 1 is inserted into the medium to be measured, because the surface of the outer sleeve 13 is in contact with the medium to be measured, and the medium to be measured is conductive, when the medium to be measured enters the outer sleeve 13, the first electrode bar 11 and the medium to be measured form a capacitor, at this time, the outer sleeve 13 can be regarded as the terminal 6 of the medium to be measured, the thickness of the coated insulating layer serves as a polar plate gap, and the capacitance is affected by the area formed by the insulating layer of the first electrode bar 11 being wrapped by the medium to be measured, the thickness of the insulating layer and the dielectric constant.

Accordingly, one of the support member 22 or the second inner sleeve 23 and the second electrode rod 21 serve as two poles of a capacitor, wherein the second electrode rod 21 is also a metal rod coated with an extremely thin and dielectric constant stable insulating layer, and the support member 22 or the second inner sleeve 23 is still made of bare metal. The reading display instrument is correspondingly connected to the support 22 and the terminal 6 of the second electrode rod 21.

It should be noted that all metal parts that level sensor in this application used in the manufacture process, including the bolt etc. all select for use corrosion-resistant stainless steel material, and different high temperature resistant macromolecular material can be selected for use according to actual installation demand to connecting piece 3. The terminal 6 is made of a high temperature resistant silver-plated wire and is connected with the outer sleeve 13, the first inner sleeve 12, the second inner sleeve 23, the support member 22, the first electrode bar 11 and the second electrode bar 21 in a welding manner, so that distributed capacitance is reduced. When the medium to be measured is corrosive, appropriate adjustment can be performed to improve the protection level.

The liquid level sensor of the embodiment of the application has the following implementation principle: inserting a liquid level sensor into a medium to be measured, measuring the capacitance of the medium to be measured with unknown height by a measuring sensor 1, measuring the capacitance of the medium to be measured with known height by a unit sensor 2, and performing proportional operation on the measured capacitances of the medium to be measured with two different heights to obtain the relatively accurate liquid level height of the medium to be measured. By modifying the first electrode rod 11 and the second electrode rod 21, the level sensor can measure the level height of the conductive medium and the non-conductive medium.

The above embodiments are preferred embodiments of the present application, and the protection scope of the present application is not limited by the above embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.

Claims

1. A liquid level sensor, characterized by: the device comprises a measuring sensor (1), a unit sensor (2) and a connecting piece (3), wherein the measuring sensor (1) and the unit sensor (2) are arranged on the same side of the connection, the end parts of the measuring sensor (1) and the unit sensor (2) far away from respective openings are connected with the connecting piece (3), and the edges of the two openings are flush;

the measuring sensor (1) is used for measuring capacitance when a medium is contained, the unit sensor (2) is used for measuring capacitance when a certain volume of medium is contained, and the respective terminals (6) of the measuring sensor (1) and the unit sensor (2) penetrate through the connecting piece (3).

2. The fluid level sensor of claim 1, wherein: measuring sensor (1) includes first electrode bar (11), first inner skleeve (12) and outer sleeve (13), first inner skleeve (12) with outer sleeve (13) coaxial setting, first inner skleeve (12) with there is certain clearance between outer sleeve (13), first electrode bar (11) set up in first inner skleeve (12) with on the axis of outer sleeve (13), first electrode bar (11) with be provided with fixed plate (7) between first inner skleeve (12).

3. The fluid level sensor of claim 2, wherein: one end of the outer sleeve (13) is fixedly arranged on the connecting piece (3), and a plurality of fixing blocks (4) are arranged between the first inner sleeve (12) and the outer sleeve (13).

4. The fluid level sensor of claim 2, wherein: the fixing plate (7) is provided with a plurality of liquid passing holes (71).

5. A liquid level sensor as claimed in claim 3, wherein: the unit sensor (2) comprises a second electrode rod (21), a support (22) and a second inner sleeve (23) with the same diameter and length as the first inner sleeve (12);

the second inner sleeve (23) is fixedly arranged on the connecting piece (3), a partition plate (8) is arranged in the second inner sleeve (23), a preset distance exists between the partition plate (8) and an opening of the second inner sleeve (23), the second inner sleeve (23) is divided into a connecting part (231) and a measuring part (232) by the partition plate (8), the measuring part (232) is close to the opening of the second inner sleeve (23), the second electrode bar (21) is arranged on the axis of the second inner sleeve (23), and the second electrode bar (21) penetrates through the partition plate (8) and is connected with the partition plate (8) in a sealing mode;

the support (22) is arranged outside the second inner sleeve (23).

6. The fluid level sensor of claim 5, wherein: the supporting piece (22) is cylindrical, a step (9) is formed in one end of the supporting piece (22) along the inner wall, and the end portion where the step (9) is located is close to an opening of the second inner sleeve (23).

7. The fluid level sensor of claim 6, wherein: the distance between the step (9) and the opening of the second inner sleeve (23) is the same as the preset distance, and the width of the step (9) in the circumferential direction of the second inner sleeve (23) is the same as the distance between the outer sleeve (13) and the first inner sleeve (12).

8. The fluid level sensor of claim 7, wherein: an air duct (221) is formed in the step (9), and the air duct (221) is communicated with the step (9) and one end, far away from the opening of the second inner sleeve (23), of the supporting piece (22).

9. The fluid level sensor of claim 8, wherein: a ventilation branch channel (222) is formed in one surface, facing the measuring part (232), of the partition plate (8);

the air duct branch (222) communicates the measurement section (232) with the air duct (221).

10. The fluid level sensor of claim 5, wherein: the plurality of fixing blocks (4) are arranged close to the ends of the first inner sleeve (12) and the outer sleeve (13).