CN115993166A - Bipolar plate self-adaptive capacitive liquid level sensing system - Google Patents
Bipolar plate self-adaptive capacitive liquid level sensing system Download PDFInfo
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- CN115993166A CN115993166A CN202310137578.0A CN202310137578A CN115993166A CN 115993166 A CN115993166 A CN 115993166A CN 202310137578 A CN202310137578 A CN 202310137578A CN 115993166 A CN115993166 A CN 115993166A
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Abstract
The invention relates to the technical field of capacitive liquid level sensing systems, in particular to a bipolar plate self-adaptive capacitive liquid level sensing system, which comprises: a first electrode plate serving as a measuring electrode plate is inserted into a container for containing a liquid medium; the second electrode plate, which serves as a reference electrode plate, is positioned in the forward projection area of the first electrode plate in the cross-sectional direction of the container. The first polar plate and the second polar plate are electrically connected with the measuring circuit; the measuring circuit obtains the liquid level and/or the liquid level change of the liquid medium based on the capacitance values of the first polar plate and the second polar plate in the air and the capacitance values of the first polar plate and the second polar plate immersed in the liquid medium. The invention also provides an improved bipolar plate self-adaptive capacitance type liquid level sensing system, an error compensation structure of the reference polar plate is designed, the capacitance value of the reference polar plate is compensated to be influenced by a connecting wire by using the wiring capacitance which is distributed in a space symmetrical mode, the capacitance measured value of the reference polar plate is kept constant, and the self-adaption and the measurement precision of the system to the change of a liquid medium are improved.
Description
Technical Field
The invention relates to the technical field of capacitive liquid level sensing systems, in particular to a bipolar plate self-adaptive capacitive liquid level sensing system.
Background
The capacitive liquid level sensing system converts the position change of a measured object into the change of capacitance, when the height of a measured medium immersed measuring electrode changes, the capacitance change is caused, and the change of the liquid level is detected by converting the circuit of the measuring system into a standard current signal to be output. The capacitive liquid level sensing system is widely applied to consumer electronics, industry, automobiles and other scenes, such as intelligent water cups, intelligent toilets, water purifiers, hydraulic systems, liquid cooling systems, vehicle-mounted oil level and other detection scenes.
In the design and use process of the capacitive liquid level sensing system, a measuring electrode needs to be inserted into a container filled with liquid, the measuring electrode is used as one pole of a capacitor, a container wall is used as the other pole of the capacitor, and a medium between the two poles comprises the liquid and gas above the liquid level. Since the dielectric constant of the liquid is different from that of the gas above the liquid level, when the liquid level rises, the total dielectric constant value between the two poles of the capacitive liquid level sensing system is increased, so that the capacitance is increased, whereas when the liquid level falls, the total dielectric constant value between the two poles is reduced, so that the capacitance is correspondingly reduced, and the liquid level change is measured through the change of the capacitance between the two poles.
The existing capacitive liquid level sensing system generally adopts a single electrode (i.e. measuring electrode) mode, so that the dielectric constant of the liquid medium must be determined in advance. Whenever the dielectric constant of the liquid medium changes, for example, the type of the medium changes or the characteristics such as the concentration of the medium change slightly, the monopole plate capacitive liquid level system needs to be calibrated again, so that the capacitive liquid level sensing system cannot adapt to the difference caused by different liquid mediums.
Disclosure of Invention
Aiming at the defects and shortcomings in the prior art, the invention aims to provide a bipolar plate self-adaptive capacitive liquid level sensing system, which is characterized in that the bipolar plates of a measuring polar plate and a reference polar plate are designed, and the measuring polar plate and the reference polar plate, namely the bipolar electrodes, are ensured to have consistent space electric fields, so that the difference caused by the change of a self-adaptive liquid medium is not required to be repeatedly calibrated again, and the detection efficiency and accuracy are improved.
According to a first aspect of the object of the present invention, a bipolar plate adaptive capacitive liquid level sensing system is presented, comprising:
a first electrode plate inserted into a container for containing a liquid medium as a measuring electrode plate;
the second polar plate is positioned right below the first polar plate and in the range of the orthographic projection area of the first polar plate in the cross section direction of the container, and the second polar plate is used as a reference polar plate;
the first polar plate and the second polar plate are electrically connected with a measuring circuit of the liquid level sensing system;
the measuring circuit is arranged to obtain the level and/or level change of the liquid medium based on the capacitance values of the first plate, the second plate in air and their immersion in the liquid medium.
As an alternative embodiment, the first plate and the second plate are provided based on the same electrode material.
As an alternative embodiment, the first and second electrode plates have the same shape and size in a cross section along the cross section direction of the container, for example, the cross section shape may be designed as a rectangle.
As an alternative embodiment, the first polar plate and the second polar plate are sequentially fixed on the surface of a substrate from top to bottom, the substrate is arranged to be vertically inserted into the container along the longitudinal axis direction of the container, and the substrate is a PCB circuit board or an insulating bottom board of the liquid level sensing system.
As an alternative embodiment, the measuring circuit is arranged to obtain the level information of the liquid medium according to the following manner:
wherein H is l Representing the liquid level; c (C) meas Representing a capacitance value of the first plate after being partially immersed by the liquid medium; c (C) meas_a Representing the capacitance value of the first polar plate in air; c (C) ref A capacitance value representing the immersion of the second plate in the liquid medium; c (C) ref_a Representing the capacitance value of the second polar plate in air; h ref Representing the height of the second plate.
Therefore, according to the bipolar plate self-adaptive capacitive liquid level sensing system implemented according to the first aspect of the invention, by designing a bipolar electrode sensing system comprising a measuring polar plate and a reference polar plate, the capacitance values of the reference polar plate and the measuring polar plate in the air are determined by ensuring that the measuring polar plate and the reference polar plate have consistent space electric fields, so that the liquid level height can be obtained only by ensuring that the capacitance value of the reference polar plate in a liquid medium is stable and unchanged during measurement. Therefore, the bipolar plate self-adaptive capacitive liquid level sensing system can adapt to the difference caused by the change of a liquid medium, does not need to repeatedly recalibrate the capacitive liquid level sensing system, and improves the detection efficiency and accuracy.
According to a second aspect of the object of the present invention, there is also presented a bipolar plate adaptive capacitive liquid level sensing system comprising:
a first electrode plate inserted into a container for containing a liquid medium as a measuring electrode plate;
the second polar plate is positioned right below the first polar plate and in the range of the orthographic projection area of the first polar plate in the cross section direction of the container, and the second polar plate is used as a reference polar plate;
one end of the first connecting wire is electrically connected with the second pole plate, and the other end of the first connecting wire is electrically connected to a measuring circuit of the liquid level sensing system;
a second connection line electrically connected to the measurement circuit of the liquid level sensing system, the second connection line being provided as an error compensation line;
the first connecting wire and the second connecting wire are positioned on the same side face of the second polar plate and are symmetrically distributed about the central axis of the second polar plate;
the measuring circuit is arranged to obtain the level and/or level change of the liquid medium based on the capacitance values of the first pole plate, the second pole plate and the second connecting line in air, and the capacitance values of the first pole plate, the second pole plate and the second connecting line immersed in the liquid medium.
As an alternative embodiment, the first and second plates have the same shape and size in a cross section along the cross section direction of the container.
As an alternative embodiment, the first polar plate and the second polar plate are sequentially fixed on the surface of a substrate from top to bottom, the substrate is arranged to be vertically inserted into the container along the longitudinal axis direction of the container, and the substrate is a PCB circuit board or an insulating bottom board of the liquid level sensing system.
As an alternative embodiment, the first connection line and the second connection line have the same line width.
As an alternative embodiment, the one end of the first connection line is electrically connected to the second electrode plate by a via.
As an alternative embodiment, the measuring circuit is arranged to obtain the level information of the liquid medium according to the following manner:
wherein H is l Representing the liquid level; c (C) meas Representing a capacitance value of the first plate after being partially immersed by the liquid medium; c (C) meas_a Representing the capacitance value of the first polar plate in air;
C ref representing an equivalent capacitance value of a second plate connected to a first connection line immersed in a liquid medium, wherein the first connection line is partially immersed and the second plate is completely immersed; c (C) er Representing a capacitance value of the second connection line partially immersed in the liquid medium;
C ref_a representing the equivalent capacitance value of the second polar plate connected with the first connecting wire in air; c (C) er Representing the capacitance value of the second connecting line in passenger air;
H ref representing the second poleThe height of the plate.
In order to further improve stability, reliability and measurement accuracy of the bipolar plate adaptive capacitance type liquid level sensing system according to the first embodiment, further solve the defect that a measured capacitance value is affected by external infection and coupling, for example, when a reference electrode plate is connected to a measurement circuit above the electrode plate through a PCB wiring or a shielding cable, the measured capacitance value can change due to the change of the height of the immersed wiring below the liquid level, and the capacitance value of the reference electrode plate is affected along with the welding sealing structure of the bottom of the cable and the reference electrode plate, so that the actual measured capacitance value is inaccurate.
It should be understood that all combinations of the foregoing concepts, as well as additional concepts described in more detail below, may be considered a part of the inventive subject matter of the present disclosure as long as such concepts are not mutually inconsistent. In addition, all combinations of claimed subject matter are considered part of the disclosed inventive subject matter.
The foregoing and other aspects, embodiments, and features of the present teachings will be more fully understood from the following description, taken together with the accompanying drawings. Other additional aspects of the invention, such as features and/or advantages of the exemplary embodiments, will be apparent from the description which follows, or may be learned by practice of the embodiments according to the teachings of the invention.
Drawings
The drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. Embodiments of various aspects of the invention will now be described, by way of example, with reference to the accompanying drawings.
FIG. 1 is a schematic diagram of a prior art capacitive liquid level sensing system employing a unipolar plate as a measurement electrode.
Fig. 2 is a schematic diagram of a capacitive liquid level sensing system employing bipolar plates in accordance with an embodiment of the first aspect of the invention.
FIG. 3 is a schematic circuit connection diagram of a capacitive liquid level sensing system employing bipolar plates in accordance with an embodiment of the first aspect of the invention.
Fig. 4 is a schematic diagram of an exemplary reference plate and measurement circuit connection via PCB wiring of the present invention.
Fig. 5 is a schematic diagram of an exemplary reference plate and measurement circuit connection of the present invention via a shielded cable.
Fig. 6 is a schematic diagram of a capacitive liquid level sensing system employing bipolar plates in accordance with an embodiment of the second aspect of the invention.
FIG. 7 is a schematic diagram of the circuit connections of a capacitive liquid level sensing system employing bipolar plates in accordance with an embodiment of the second aspect of the invention.
FIG. 8 is a schematic diagram of a symmetrical distribution of error compensation lines and first connection lines in accordance with an example of the present invention.
The definition of the individual reference numerals in fig. 1 to 8 is as follows:
100-a substrate; 101-a first polar plate; 102-a second plate; 103 a measurement circuit; 104-PCB wiring; 105-shielded cable; 106, welding spot sealing positions; 107; a first connecting line; 108-a second connecting line; 109-vias;
200-a liquid medium; 201-liquid level.
Detailed Description
For a better understanding of the technical content of the present invention, specific examples are set forth below, along with the accompanying drawings.
Aspects of the invention are described in this disclosure with reference to the drawings, in which are shown a number of illustrative embodiments. The embodiments of the present disclosure are not necessarily intended to include all aspects of the invention. It should be understood that the various concepts and embodiments described above, as well as those described in more detail below, may be implemented in any of a number of ways, as the disclosed concepts and embodiments are not limited to any implementation. Additionally, some aspects of the disclosure may be used alone or in any suitable combination with other aspects of the disclosure.
The example shown in fig. 1 illustrates a typical design of a single-plate capacitive liquid level sensing system in existing designs, in which a single measuring plate is inserted into a container containing a liquid medium 200. The liquid level 201 height information is calculated based on the capacitance of the individual measuring plates into the liquid medium and the position air. For ease of reference, in the example shown in fig. 1, a single measurement plate is identified with a first plate 101.
With reference to FIG. 1, the liquid level H l The calculation principle and process of (a) are as follows:
wherein, epsilon l And H l Respectively represent the dielectric constant and the liquid level height, ε, of the liquid medium 200 a And H a Respectively the dielectric constant and the height of air, H is the overall height of the measuring polar plate, d is the equivalent diameter of a container for containing liquid medium, delta C is the parasitic capacitance of the measuring polar plate, C m For measuring the capacitance value measured by the circuit.
In case the influence of deltac is ignored, it is possible to obtain:
thus, the height information of the liquid surface 201, that is, the liquid surface height H, can be calculated l 。
Therefore, in the unipolar capacitive liquid level sensing system, the dielectric constant of the liquid medium needs to be clarified to effectively measure the liquid level information, and the unipolar capacitive liquid level system needs to be recalibrated whenever the dielectric constant of the liquid medium changes, for example, the characteristics of the medium change, the medium concentration and the like change.
In view of this, in an embodiment of the first aspect of the present invention, a bipolar plate capacitive liquid level sensing system is provided, where a bipolar sensing system including a measuring plate and a reference plate is designed, and by ensuring that the measuring plate and the reference plate have uniform space electric fields, the capacitance values of the reference plate and the measuring plate in air are determined, so that the liquid level can be obtained only by ensuring that the capacitance value of the reference plate in the liquid medium is stable and unchanged during measurement.
Fig. 2 and 3 illustrate exemplary implementations of bipolar plate capacitive fluid level sensing systems in accordance with embodiments of the first aspect of the invention. The bipolar plate capacitive liquid level sensing system as illustrated in the examples of fig. 2 and 3 includes a first plate 101 and a second plate 102, each electrically connected to a measurement circuit 103 of the liquid level sensing system.
As shown in fig. 2, the first plate 101 is inserted into a container for containing a liquid medium as a measuring plate. The second plate 102 is located at a position directly below the first plate 101 and within a forward projection area of the first plate in the cross-sectional direction of the container, and the second plate 102 is provided as a reference plate.
It will be appreciated that the first plate 101, which is a measuring plate, is typically sized to cover the entire height of the interior of the container. A second plate 102, which is a reference plate, is located at the bottom of the liquid level sensing system, directly below the first plate 101, and remains the same as the first plate 101 in width and position.
In the mounting manner, the first electrode plate 101 and the second electrode plate 102 are sequentially fixed on the surface of a substrate 100 from top to bottom, and the substrate 100 is vertically inserted into the container along the longitudinal axis direction of the container. The first plate 101 and the second plate 102 are positioned on the same side surface of the plates, thereby ensuring that the measuring plate and the reference plate have a highly uniform space electric field.
The substrate 100 is a PCB or an insulating base plate of the liquid level sensor system.
As an alternative embodiment, the first plate 101 and the second plate 102 are provided based on the same electrode material.
As an alternative embodiment, the first pole plate 101 and the second pole plate 102 have the same shape and size in a cross section along the cross section direction of the container, for example, the cross section is designed as a rectangle or a disc.
The measurement circuit 103 is arranged to obtain the level and/or level change of the liquid medium based on the capacitance values of the first pole, 101, the second pole plate 102 in air, and their capacitance values immersed in the liquid medium 200.
In connection with the example shown in fig. 2, the liquid level height H l The calculation principle and process of (a) are as follows:
wherein C is maes_a The capacitance of the measuring plate in air is expressed as:
C ref_a the capacitance value of the reference electrode plate in air is expressed as:
C ref indicating that the reference electrode plate is immersed in the liquidThe capacitance in the bulk medium is expressed as:
C meas the capacitance value representing the measurement plate after being partially immersed in the liquid medium can be expressed as:
can be further expressed as:
wherein H is the overall height of the first plate 101; h ref Representing the overall height of the second plate 102.
ε l And H l Respectively represent the dielectric constant and the liquid level height, ε, of the liquid medium 200 a And H a The dielectric constant and the height of air, respectively, d being the equivalent diameter of the container holding the liquid medium.
Wherein DeltaC meas 、ΔC ref The parasitic capacitances of the first plate 101 and the second plate 102 are shown, respectively.
Thus, the height information of the liquid surface 201, i.e., the liquid surface height H, can be calculated while neglecting parasitic capacitance l ：
As described previously, C meas Representing the capacitance value of the first plate 101 after it is partially immersed in the liquid medium; c (C) meas_a Representing the capacitance value of the first polar plate in air; c (C) ref A capacitance value representing the immersion of the second plate in the liquid medium; c (C) ref_a Representing the capacitance of the second plate in air.
Thus, in the example shown in fig. 2, since the capacitance values of the reference plate and the measurement plate in air are determined, it is only necessary to ensure that the capacitance value of the reference plate in the liquid medium is stable and unchanged, so that the liquid level is ensured to be available.
Therefore, the bipolar plate self-adaptive capacitive liquid level sensing system can adapt to the difference caused by the change of a liquid medium, does not need to repeatedly recalibrate the capacitive liquid level sensing system, and improves the detection efficiency and accuracy.
Fig. 4, 5 show an illustration of the connection of the second plate 102 immersed in a liquid medium with the measurement circuit 103 (usually arranged above the container) via PCB wiring 104 or shielding cables 105, respectively.
In the connection structure adopting the PCB wiring method, as shown in fig. 4, no matter how small the line width of the PCB wiring is (as much as possible), the capacitance value of the reference electrode plate is changed along with the change of the height of the wiring immersed under the liquid level, so that the measurement result is disturbed by external connection, resulting in inaccuracy.
In connection with fig. 5, in the connection structure using the shielded cable method, the bottom of the shielded cable 105 is welded to the reference plate, and the welding point 106 in the example shown in fig. 5 is sealed, so that the welded portion must be completely and reliably sealed to prevent the penetration of liquid due to molecular movement, thereby affecting the capacitance value of the reference plate for a long period of time. Meanwhile, in the production process and the application scene, the shielding cable and the welding spot sealing structure are immersed in various liquid media, and the shielding cable and the welding spot sealing structure possibly need to bear the influences of vibration, drop, collision and the like in the storage and transportation process and the working process, so that the production and maintenance cost of the process is difficult to measure.
It should be appreciated that in the various embodiments of the present invention described above and below, the first plate may be electrically connected to the measurement circuitry, typically by way of a top wiring.
Therefore, on the basis of the foregoing first embodiment of the present invention, as shown in fig. 6 and 7, an improved bipolar plate adaptive capacitive liquid level sensing system is further provided, which solves the defect that the measured capacitance value is affected by external infection and coupling, and further improves the stability, reliability and measurement accuracy of the liquid level sensing system.
The bipolar plate adaptive capacitive liquid level sensing system, as illustrated in the examples of fig. 6 and 7, includes a first plate 101, a second plate 102, a first connection line 107, a second connection line 108, and a measurement circuit 103.
The first plate 101, which is a measuring plate, is inserted into a container for containing a liquid medium in the same manner as the first embodiment described above. The second plate 102, which is a reference plate, is located at a position directly below the first plate and within the forward projection area of the first plate in the cross-sectional direction of the container.
As shown in fig. 6 and 7, the first connection line 107 has one end electrically connected to the second electrode plate and the other end electrically connected to the measurement circuit 103 of the liquid level sensing system. As an alternative example, the one end of the first connection line 107 is electrically connected to the second electrode plate in a via manner. In the example shown in fig. 8, reference numeral 109 denotes a via hole (metallized hole).
The second connection line 108 is electrically connected to the measurement circuit 103 of the liquid level sensing system. The second connection line is provided as an error compensation line.
As shown in fig. 6 and 8, the first connection line 107 and the second connection line 108 are located on the same side of the second plate 102 and are symmetrically arranged about the central axisbase:Sub>A-base:Sub>A of the second plate.
As an alternative embodiment, the first connection line 107 and the second connection line 108 have the same line width, and are designed in particular to be as small as possible.
In the example in connection with fig. 6, 7, the measurement circuit 103 is arranged to obtain the level and/or the level change of the liquid medium based on the capacitance values of the first plate 101, the second plate 102 and the second connection line 108 in air, and their capacitance values immersed in the liquid medium.
In connection with the examples shown in fig. 6, 7, in the bipolar plate adaptive capacitive level sensing system of this second embodiment, the fluid level height H l The calculation principle and process of (a) are as follows:
the capacitance of the second plate 102 (including the connection lines) in air is:
the capacitance value of the second pole plate 102 immersed in the liquid medium is:
wherein the first connection line 107 is partially submerged and the second plate 102 is completely submerged;
the capacitance of the second connection line 108 in air is:
the capacitance value of the second connection line 108 after being partially immersed by the liquid medium is:
from the above formula, it can be seen that:
thus, there are:
wherein the measuring electrode plate is in the airCapacitance value C maes_a And measuring capacitance C of the plate partially immersed in the liquid medium meas The definition and the calculation manner of (a) are the same as those in the foregoing first embodiment.
The first connection line 107 and the second connection line 108 can be designed identically, and the line width is the same, and ΔC 'is used in the embodiment of the present invention' ref The parasitic capacitances of the first connection line 107 and the second connection line 108 are shown. d' represents the equivalent line width of the first connection line 107 and the second connection line 108.
Combining the above liquid level height H l Since the first connection line and the second connection line are strictly spatially symmetrically distributed (except for the via hole), the calculation principle of (C) ref -C er ) And (C) ref_a -C er_a ) The value of (2) remains fixed, so that the measured level H l Independent of the dielectric constant of the liquid medium.
It can be seen that in the embodiment of the second aspect of the present invention, an error compensation structure of the reference plate is designed to compensate the capacitance value of the reference plate by using the wiring capacitance (compensation capacitance constructed by the second connection line) which is spatially symmetrically distributed, while keeping the capacitance measurement value of the reference plate constant.
Furthermore, by combining the design of the improved bipolar plate self-adaptive capacitive liquid level sensing system of the second embodiment and matching with a multi-channel (more than 3 channels) high-precision capacitance measuring circuit, the high-precision self-adaptive capacitive liquid level system with the error compensation structure can maintain the self-adaptability of the system under the conditions of liquid medium replacement and medium characteristic change. Meanwhile, the PCB can be used for batch design and manufacture with lower BOM and process cost.
While the invention has been described with reference to preferred embodiments, it is not intended to be limiting. Those skilled in the art will appreciate that various modifications and adaptations can be made without departing from the spirit and scope of the present invention. Accordingly, the scope of the invention is defined by the appended claims.
Claims (11)
1. A bipolar plate adaptive capacitive liquid level sensing system, comprising:
a first electrode plate inserted into a container for containing a liquid medium as a measuring electrode plate;
the second polar plate is positioned right below the first polar plate and in the range of the orthographic projection area of the first polar plate in the cross section direction of the container, and the second polar plate is used as a reference polar plate;
the first polar plate and the second polar plate are electrically connected with a measuring circuit of the liquid level sensing system;
the measuring circuit is arranged to obtain the level and/or level change of the liquid medium based on the capacitance values of the first plate, the second plate in air and their immersion in the liquid medium.
2. The bipolar plate adaptive capacitive liquid level sensing system of claim 1, wherein the first plate and the second plate are configured to be fabricated based on the same electrode material.
3. The bipolar plate adaptive capacitive liquid level sensing system of claim 1, wherein the first and second plates have the same shape and size in cross-section along the cross-sectional direction of the vessel.
4. The bipolar plate adaptive capacitive liquid level sensing system of claim 1, wherein the first and second plates are sequentially secured to a surface of a substrate from top to bottom, the substrate configured to be vertically inserted into the container along a longitudinal axis of the container, the substrate being a PCB circuit board or an insulating base plate of the liquid level sensing system.
5. The bipolar plate adaptive capacitive liquid level sensing system of any one of claims 1-5, wherein the measurement circuit is configured to obtain liquid level information of the liquid medium according to:
wherein H is l Representing the liquid level; c (C) meas Representing a capacitance value of the first plate after being partially immersed by the liquid medium; c (C) meas_a Representing the capacitance value of the first polar plate in air; c (C) ref A capacitance value representing the immersion of the second plate in the liquid medium; c (C) ref_a Representing the capacitance value of the second polar plate in air; h ref Representing the height of the second plate.
6. A bipolar plate adaptive capacitive liquid level sensing system, comprising:
a first electrode plate inserted into a container for containing a liquid medium as a measuring electrode plate;
the second polar plate is positioned right below the first polar plate and in the range of the orthographic projection area of the first polar plate in the cross section direction of the container, and the second polar plate is used as a reference polar plate;
one end of the first connecting wire is electrically connected with the second pole plate, and the other end of the first connecting wire is electrically connected to a measuring circuit of the liquid level sensing system;
a second connection line electrically connected to the measurement circuit of the liquid level sensing system, the second connection line being provided as an error compensation line;
the first connecting wire and the second connecting wire are positioned on the same side face of the second polar plate and are symmetrically distributed about the central axis of the second polar plate;
the measuring circuit is arranged to obtain the level and/or level change of the liquid medium based on the capacitance values of the first pole plate, the second pole plate and the second connecting line in air, and the capacitance values of the first pole plate, the second pole plate and the second connecting line immersed in the liquid medium.
7. The bipolar plate adaptive capacitive liquid level sensing system of claim 6, wherein the first and second plates have the same shape and size in cross-section along the cross-sectional direction of the vessel.
8. The bipolar plate adaptive capacitive liquid level sensing system of claim 6, wherein the first and second plates are sequentially secured to a surface of a substrate from top to bottom, the substrate configured to be vertically inserted into the container along a longitudinal axis of the container, the substrate being a PCB circuit board or an insulating base plate of the liquid level sensing system.
9. The bipolar plate adaptive capacitive liquid level sensing system of any one of claims 6-8, wherein the first and second connection lines have the same line width.
10. The bipolar plate adaptive capacitive liquid level sensing system of any one of claims 6-8, wherein said one end of said first connection line is electrically connected to a second plate by way of a via.
11. The bipolar plate adaptive capacitive liquid level sensing system of any one of claims 6-8, wherein the measurement circuit is configured to obtain liquid level information of the liquid medium according to:
wherein H is l Representing the liquid level; c (C) meas Representing a capacitance value of the first plate after being partially immersed by the liquid medium; c (C) meas_a Representing the capacitance value of the first polar plate in air;
C ref representing an equivalent capacitance value of a second plate connected to a first connection line immersed in a liquid medium, wherein the first connection line is partially immersed and the second plate is completely immersed; c (C) er Indicating that the second connection line is partially submerged in the liquid mediumA capacitance value;
C ref_a representing the equivalent capacitance value of the second polar plate connected with the first connecting wire in air; c (C) er Representing the capacitance value of the second connecting line in passenger air;
H ref representing the height of the second plate.
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| CN117433605A (en) * | 2023-09-14 | 2024-01-23 | 北京天海工业有限公司 | Capacitive sensor, capacitive liquid level meter and low-temperature welding heat-insulating gas cylinder |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117433605A (en) * | 2023-09-14 | 2024-01-23 | 北京天海工业有限公司 | Capacitive sensor, capacitive liquid level meter and low-temperature welding heat-insulating gas cylinder |
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