Patent ID: 12215996

DETAILED DESCRIPTION OF THE INVENTION

There are embodiments of the present invention below to explain its implementation examples in particular embodiments. Nevertheless, this disclosure itself is not intended to limit the scope of the rights granted by this patent. It should rather be assumed that the claimed invention can also be implemented in other ways so that the claimed invention will include different elements and conditions or combinations of elements and conditions similar to the elements and conditions described herein in combination with other existing and future technologies.

According to the preferred embodiment of the present invention, there is provided a capacitive level sensor comprising a base; a sensitive element; therewith the base comprises at least first part having a recess with a cover to hermetically house a computing unit, as well as a hole for the computing unit's output cable; second part having holes for expansion sleeves mostly in the center, in the area of the first part, holes for fasteners in the side, vent holes in the side; therewith the sensitive element is an electrode housing, which is a metal section formed by at least two tubes of equal or unequal length that are connected to each other at least partially along the length of said metal section, which optionally comprises at least one stiffener extending along the entire length of said metal section and connecting at least the two adjacent tubes of the section; therewith each tube of the section has either a vent hole aligned axially with the corresponding vent hole in the lateral side of the collar part or a slit aligned axially with the corresponding vent hole in the lateral side of said collar part and arranged at least partially lengthwise at least in one side adjacent to the measured medium; therewith the electrode housing contains electrodes rigidly fixed in each tube of the section, and these electrodes are metal tubes having the same unit-length capacitance but differing in their length, and the main electrode is mostly as long as the electrode housing, and each compensation electrode is shorter than the main electrode; therewith the sensitive element is connected to the base through holes for fasteners; therewith the main electrode and each compensation electrode are connected to the computing unit by means of metal rods connected to expansion sleeves, which are connected to holes for expansion sleeves.

According to an alternative embodiment of the present invention, there is provided said sensor, wherein the base is made of a metal or copolymer or combinations thereof.

According to another alternative embodiment of the present invention, there is provided said sensor, wherein the connection between the metal rods and expansion sleeves is a thread joint.

According to another alternative embodiment of the present invention, there is provided said sensor, wherein the expansion sleeves are made of a dielectric material.

According to another alternative embodiment of the present invention, there is provided said sensor, wherein the connection between the expansion sleeves and holes for expansion sleeves is a thread joint.

According to another alternative embodiment of the present invention, there is provided said sensor, wherein the thread joint between the expansion sleeves and holes for expansion sleeves contains a sealant.

According to another alternative embodiment of the present invention, there is provided said sensor, wherein the expansion sleeves have sealing rings.

According to another alternative embodiment of the present invention, there is provided said sensor, wherein the hole located in the recess and intended for the output cable of the computing unit contains a sealant.

According to another alternative embodiment of the present invention, there is provided said sensor, wherein the vent holes are arranged asymmetrically in terms of their vicinity to the base.

According to another alternative embodiment of the present invention, there is provided said sensor, wherein the main electrode and each compensation electrode are covered with an insulation wrap.

According to another alternative embodiment of the present invention, there is provided said sensor, wherein the sensitive element is formed by connecting at least two geometrically similar sensitive elements of equal or unequal length by means of a coupling sleeve.

According to another alternative embodiment of the present invention, there is provided said sensor, wherein there are coaxial slits, which are cut mostly along the entire length of the coupling sleeve body, in each side of the coupling sleeve body adjacent to said slits in the electrode housing.

According to another alternative embodiment of the present invention, there is provided said sensor, wherein the main electrode and each compensation electrode are made of the same material as the metal rods.

According to another alternative embodiment of the present invention, there is provided said sensor, wherein the main electrode and each compensation electrode, the metal rods, and electrode housing are made of the same material.

According to another alternative embodiment of the present invention, there is provided said sensor, wherein each tube of the section has a slit along its entire length at least in one side adjacent to the measured medium.

According to another preferred embodiment of the present invention, there is provided a sensitive element for the capacitive level sensor, being an electrode housing, which is a metal section formed by at least two tubes of equal or unequal length that are connected to each other at least partially along the length of said metal section, which optionally comprises at least one stiffener extending along the entire length of said metal section and connecting at least the two adjacent tubes of the section; therewith each tube of the section has either a vent hole aligned axially with the corresponding vent hole in the lateral side of the collar part of the base of the capacitive level sensor or a slit aligned axially with the corresponding vent hole in the lateral side of said collar part of the base of the capacitive level sensor and arranged at least partially lengthwise at least in one side adjacent to the measured medium; therewith the electrode housing contains electrodes rigidly fixed in each tube of the section, and these electrodes are metal tubes having the same unit-length capacitance but differing in their length, and the main electrode is mostly as long as the electrode housing, and each compensation electrode is shorter than the main electrode.

According to another alternative embodiment of the present invention, there is provided said sensitive element, wherein the main electrode and each compensation electrode are covered with an insulation wrap.

According to another alternative embodiment of the present invention, there is provided said sensitive element that is formed by connecting at least two geometrically similar electrodes of equal or unequal length by means of a coupling sleeve.

According to another alternative embodiment of the present invention, there is provided said sensitive element, wherein there are coaxial slits, which are cut mostly along the entire length of the coupling sleeve body, in each side of the coupling sleeve body adjacent to said slits in the electrode housing.

According to another alternative embodiment of the present invention, there is provided said sensitive element, wherein the main electrode and each compensation electrode, the electrode housing, and coupling sleeve are made of the same material.

According to another alternative embodiment of the present invention, there is provided said sensitive element, wherein each tube of the section has a slit along its entire length at least in one side adjacent to the measured medium.

According to another alternative embodiment of the present invention, there is provided said sensitive element, wherein each tube of the section has a slit along its entire length at least in one side adjacent to the measured medium.

According to another preferred embodiment of the present invention, there is provided an electrode housing for the capacitive level sensor, being a metal section formed by at least two tubes of equal length that are connected to each other at least partially along the length of said metal section, which optionally comprises at least one stiffener extending along the entire length of said metal section and connecting at least the two adjacent tubes of the section; therewith each tube of the section has either a vent hole aligned axially with the corresponding vent hole in the lateral side of the collar part of the base of the capacitive level sensor or a slit aligned axially with the corresponding vent hole in the lateral side of said collar part of the base of the capacitive level sensor and arranged at least partially lengthwise at least in one side adjacent to the measured medium;

According to another alternative embodiment of the present invention, there is provided said housing, wherein each tube of the section has a slit along its entire length at least in one side adjacent to the measured medium.

According to another preferred embodiment of the present invention, there is provided a measured medium flow monitoring system comprising one or more capacitive level sensors installed in one or more reservoirs with measured media, wherein the sensors are configured to communicate with a server to provide user information about the level in a reservoir in which said sensor is installed.

According to another alternative embodiment of the present invention, there is provided said system, wherein said capacitive sensors and server communicate with each other by means of a transceiver.

According to another alternative embodiment of the present invention, there is provided said system, wherein the transceiver further comprises one or more navigation unit connected to the server, and each navigation unit is associated with said single sensor or a single group of said sensors and configured to transfer information about the location of the corresponding sensor or group of sensors to the server.

According to another preferred embodiment of the present invention, there is provided a reservoir for a measured medium, containing said capacitive sensor optionally comprising said coupling sleeve.

According to another alternative embodiment of the present invention, there is provided a reservoir for a measured medium, containing one or more said capacitive level sensors according to any of said embodiments of the present invention.

According to another preferred embodiment of the present invention, there is provided a method for assembling the capacitive level sensor, consisting of the following steps: (A) connecting the capacitive sensor base with expansion sleeves connected to metal rods; (B) installing the computing unit into the recess for the computing unit in the capacitive sensor base and connecting the computing unit with said metal rods; (C) connecting the output cable to the input of said computing unit; (D) installing the cover protecting the recess for said computing unit and sealing it with a compound through the threaded hole to connect the output cable; (E) screwing the output cable into said threaded hole; (F) pre-calibrating the capacitive sensor after the compound has cured; (G) screwing electrodes onto the metal rods; (H) installing the electrode housing by stringing it on the electrodes and by rigidly fixing the electrode housing in the collar part of the base, therewith the electrodes may be optionally secured inside the electrode housing.

According to another preferred embodiment of the present invention, there is provided said method for assembling, wherein at step (F), the values obtained from the compensation measuring channels, which are one or more channels formed by one or more of the metal rods, are normalized by the value obtained from the main measuring channel, which is the only channel formed by only one of the metal rods, and correction factors are calculated and recorded into the non-volatile memory of the computing unit.

According to another preferred embodiment of the present invention, there is provided said method for assembling, wherein the electrode housing is rigidly fixed with pop rivets in the collar part of the base, and electrodes are secured with spacer rings inside the electrode housing.

According to another alternative embodiment of the present invention, there is provided said method for assembling, wherein at step (G), the electrodes are provided with insulation wrap.

According to another preferred embodiment of the present invention, there is provided a method for pre-calibrating the capacitive level sensor during the assembly of the sensor, consisting of the following steps: (A) measuring the capacitance of the main measuring channel, which is only one of the metal rods connected to the computing unit of the capacitive sensor, as part of the pre-calibration procedure; (B) measuring the capacitance of each compensation measuring channel, which is one or more of the metal rods connected to the computing unit of the capacitive sensor, as part of the pre-calibration procedure; (C) calculating the differences between each capacitance value of the compensation measuring channel and the capacitance value of the main measuring channel by means of a microcontroller of said computing unit; (D) iteratively repeating the operations of steps (A) to (C) for a period in order to obtain a set of primary correction factors; (E) calculating the averaged value of the correction factor by means of said microcontroller, based on the set of primary correction factors and storing the resulting averaged value of the correction factor into the non-volatile memory of said computing unit.

According to another alternative embodiment of the present invention, there is provided said method for pre-calibrating, wherein at step (D), the operations of steps (A) to (C) are repeated for a maximum of 30 minutes.

According to another alternative embodiment of the present invention, there is provided said method for pre-calibrating, wherein at steps (A) and (B), the measured capacitance values may be optionally normalized by the corresponding capacitance values at the reference temperature by using the temperature compensation factor, the value of which has previously been recorded into the non-volatile memory of the computing unit, and at step (C), the resulting normalized capacitance values of the measuring channels are used as the capacitance values of the measuring channels.

According to another preferred embodiment of the present invention, there is provided a method for level measuring by means of the capacitive level sensor, consisting of the following steps: (A) calibrating the sensor in order to obtain calibration values of the capacitance difference and values of the dynamic level range to be recorded into the non-volatile memory of the sensor's computing unit, by using a measured reference medium; (B) measuring the level by means of the calibrated sensor, therewith the measurement consists of the following steps: (B1) filling a reservoir with a measured medium to the level at which the longest compensation channel of the sensor is at least partially immersed in the measured medium, while the measured medium differs from the reference medium; or filling a reservoir with a measured reference medium to any permissible level for this reservoir; (B2) measuring the capacitance values of the main measuring channel and each compensation measuring channel of the sensor for the reservoir that contains the measured medium, therewith each measurement of the capacitance value of each compensation measuring channel is carried out taking into account the average correction factor, the value of which is stored in the non-volatile memory of the computing unit; (B3) calculating values of the capacitance difference by means of the microcontroller of the computing unit by using each capacitance value of the compensation measuring channel obtained at step (B2) and the capacitance value of the main measuring channel obtained at step (B2) pairwise in order to obtain values of the capacitance difference; (B4) comparing the values of the capacitance difference obtained at step (B3) to the calibration values of the capacitance difference and calculating the ratio between these capacitance differences, which is the correction factor, by means of the microcontroller of the computing unit in order to obtain the value of the correction factor; (B5) normalizing each capacitance value of the main measuring channel by the capacitance value of the level by means of the microcontroller of the computing unit by using the correction factor, the value of which was obtained at step (B4), in order to obtain the capacitance value of the level; (B6) using the resulting values of the level by means of the microcontroller of the computing unit in order to determine the relative level according to the values of the dynamic range.

According to another alternative embodiment of the present invention, there is provided said method for level measuring, wherein at step (A), the sensor is calibrated as follows: (A1) installing the sensor in a reservoir that does not contain any measured medium; (A2) measuring the capacitance values of the main measuring channel and each compensation measuring channel of the sensor for the reservoir that does not contain any measured medium, therewith each measurement of the capacitance value of each compensation measuring channel is carried out taking into account the average correction factor, the value of which is stored in the non-volatile memory of the computing unit; (A3) filling the reservoir with a measured reference medium to the maximum permissible level for this reservoir; (A4) measuring the capacitance values of the main measuring channel and each compensation measuring channel of the sensor for the reservoir that contains the measured reference medium, therewith each measurement of the capacitance value of each compensation measuring channel is carried out taking into account the average correction factor, the value of which is stored in the non-volatile memory of the computing unit; (A5) calculating calibration values of the capacitance difference by means of the microcontroller of the computing unit by using each capacitance value of the compensation measuring channel obtained at steps (A2) and (A4) and the capacitance value of the main measuring channel obtained at steps (A2) and (A4) pairwise, based on the values obtained at steps (A2) and (A4), and recording the resulting calibration values of the capacitance difference into the non-volatile memory of the computing unit; (A6) calculating a dynamic level range by means of the microcontroller of the computing unit, based on the values obtained at steps (A2) and (A4) preceding to, simultaneously with, or after step (A5), with the dynamic level range being the difference between the capacitance value of the main measuring channel for the full reservoir and the capacitance value of the main measuring channel for the empty reservoir, and recording the resulting values of the dynamic level range into the non-volatile memory of the computing unit.

According to another alternative embodiment of the present invention, there is provided said method, wherein to obtain normalized capacitance values of the measuring channels for the reservoir that does not contain any measured medium at step (A2), the capacitance values of the measuring channels measured at step (A2) are normalized by the capacitance values of the measuring channels at the reference temperature by means of the microcontroller of the computing unit by using the temperature compensation factor, the value of which has previously been recorded into the non-volatile memory of the computing unit; to obtain normalized capacitance values of the measuring channels for the reservoir that contains the measured reference medium at step (A4), the capacitance values of the measuring channels measured at step (A4) are normalized by the capacitance values of the measuring channels at the reference temperature by means of the microcontroller of the computing unit by using the temperature compensation factor, the value of which has previously been recorded into the non-volatile memory of the computing unit; therewith at steps (A5) and (A6), the corresponding normalized capacitance values of the measuring channels are used.

According to another alternative embodiment of the present invention, there is provided said method, wherein to obtain normalized capacitance values of the measuring channels for the reservoir that contains the measured medium at step (B2), the capacitance values of the measuring channels measured at step (B2) are normalized by the capacitance values of the measuring channels at the reference temperature by means of the microcontroller of the computing unit by using the temperature compensation factor, the value of which has previously been recorded into the non-volatile memory of the computing unit; therewith at step (B3), the corresponding normalized capacitance values of the measuring channels are used.

According to another preferred embodiment of the present invention, there is provided a coupling sleeve for the electrode housing of the capacitive level sensor, being a cylinder that follows the shape of the cross-section of the electrode housing of the capacitive level sensor preferably in its cross-section or at least the cross-section of holes in its base and has slits in its side, which are cut mostly along the entire height of the coupling sleeve and span a larger area of the lateral surface.

According to another alternative embodiment of the present invention, there is provided said coupling sleeve, wherein slit-free portions of the coupling sleeve side are adapted not to obstruct the slits of the electrode housing of said capacitive level sensor when connected to said electrode housing if the electrode housing of said capacitive level sensor has slits.

According to another alternative embodiment of the present invention, there is provided said coupling sleeve that is made of the same material as the electrodes, electrode housing, and connecting rods of the capacitive level sensor.

As an example, but not a limitation,FIG.1shows an exemplary preferred embodiment of the claimed capacitive level sensor100(the sensor100). As can be seen fromFIG.1, the claimed sensor100generally consists of a base1010and an electrode housing1020, which, when it contains electrodes, is the sensitive element of the sensor100.

As an example, but not a limitation,FIG.2shows an exemplary general view of components constituting one of the preferred embodiments of the claimed sensor100. As can be seen fromFIG.2, the components constituting the sensor100may represent a base1010; a housing1020for electrodes1031,1032, optionally with at least one stiffener1021and optionally with at least one coupling sleeve1028(FIG.22); electrodes1031,1032optionally with spacer rings1033; expansion sleeves1040optionally with sealing rings1041; connecting metal rods1050; a computing unit1060.

The base1010is designed to house the computing unit1060, which is detailed below, and to connect the electrodes1031,1032of the sensor to the input of the computing unit1060. The base1010is most typically shaped as a collar flange, the first part of which, for example, without limitation, is a flat part1011and may be of any shape (including a circle, ellipse, polygon, etc.), and the second part of which, for example, without limitation, is a collar part1012and is shaped as, preferably, but not limited to, a hub with a bore of any shape (including a circle, ellipse, polygon, etc.). As it will become apparent to those skilled in the art upon reading the text below, the shape of the hub and, accordingly, that of the collar part1012bore are mainly determined by the cross-section shape of the housing1020for the electrodes1031,1032of the sensor and are selected to provide secure fixation of the housing1020for the electrodes1031,1032inside the collar part1012. Aside from this, the base1010does not have a through hole in the center of the collar part1012as contrasted to a conventional collar flange, but has several threaded through holes (not shown in the drawings), the number of which corresponds to the number of the electrodes1031,1032of the sensor. These threaded holes are arranged to provide such placement of the housing1020for the electrodes1031,1032that mounting holes1022,1023of the tubes of the housing1020for the electrodes1031,1032are aligned axially with the corresponding threaded holes. To fix the housing1020for the electrodes1031,1032to the collar part1012, there are holes10121for fasteners, which may be, not limited to, pop rivets, in the collar part's sides. Aside from this, the collar part1012has preferably, although not necessarily vent holes10122in its opposite sides as well. These vent holes are preferably arranged asymmetrically in terms of their vicinity to the flat part1011and are designed to allow a gas (a mixture of gases) to enter the housing1020for the electrodes1031,1032and to provide the same level of a measured medium in communicating vessels, one of which is said housing1020, and the other is a reservoir for a measured medium. Aside from this, the flat part1011has a recess1013for the computing unit1060on the side reverse to the side on which the collar part1012is located. As it will become apparent to those skilled in the art upon reading the text below, the recess1013may be of any shape (including a circle, ellipse, polygon, etc.), and it is mainly determined by the shape of the printed circuit board of the computing unit1060. Nevertheless, the shape of the recess1013should allow the recess to be securely sealed with a compound after the installation of the computing unit1060, followed by the installation of a cover1014for the recess1013. Aside from this, the shape of the recess1013should allow a connector-equipped output cable1063of the computing unit1060to go through a hole1015in the recess1013. Aside from this, the recess1013with the computing unit1060installed therein and covered with the cover1014for the recess1013may be further covered with a cover1070preferably made of copolymer materials, such as polyacetal, polyamide, polycarbonate, or similar materials, and shaped to provide for sufficient coverage of the recess1013.

The base1010is preferably made of a metal. Nevertheless, if sufficient stiffness is provided, the base1010may also be made of a copolymer or its combinations, including those with a metal. Preferably, the base1010is injection molded or milled.

The housing1020for the electrodes1031,1032(the housing1020) is a metal section formed by at least two tubes of equal or unequal (e.g. when there is no coupling sleeve, and the compensation electrode1032is shorter than the main electrode1031) length that are connected to each other at least partially along the length of said metal section. The housing1020may optionally comprise one or more stiffeners1021that preferably, although not necessarily extend along the entire length of the housing1020and are in contact with each tube or at least with two adjacent tubes. Said tubes have mounting holes1022,1023, and inlet holes1024,1025(not shown inFIG.2). As can be seen fromFIG.2, there are preferably vent holes10201in the place where said housing1020connects to said collar part1012of said base1010. These holes are to be aligned axially with the corresponding vent holes10122in the collar part1012, thereby allowing air to enter said housing1020. Aside from this, each tube may have at least one slit1026(for example,FIG.3) arranged at least partially lengthwise at least in one side adjacent to the measured medium. The slit1026is preferably cut along the entire length of each tube. The slit width is preferably up to 15 mm. Although it is also preferable that the slits1026in each tube are arranged symmetrically or at equal angles to each other, nevertheless, the slits1026may be arranged otherwise, for example, without limitation, at unequal angles to each other. At the same time, the main purpose of the slits1026is to provide access of a measured medium to the housing1020from the side of each tube containing the electrode1031or1032. On this basis, the slits1026should be aligned axially with the vent holes10122in the place where said housing1020connects to said collar part1012of said base1010, thereby allowing a gas (a mixture of gases) to enter said housing1020. There are holes1027in the base of the housing1020. These holes are aligned axially with the holes10121in the collar part1012of the base1010, through which the housing1020and the base1010are fastened together. Thus, as contrasted to the prototype and similar devices, the presence of the slit1026enables inertia-free measurements and rules out the clogging of the tube due to measured medium paraffinization, which will consequently lead to a greater increase in the reliability and manufacturability of the design as well as to an increase in the accuracy of level measurements.

As an example, but not a limitation,FIG.3-21shows possible exemplary cross-sections of the tubes forming the housing1020. In this case, it is preferable, although not necessarily that the shape of the electrodes1031,1032also changes depending on the tube cross-section to correspond to the cross-section of the tubes forming the housing1020—owing to this, a larger area of the capacitor can be provided, which will allow more accurate measurements. At the same time, although the possible exemplary cross-sections of the tubes (seeFIG.3-21) forming the housing1020have the slits1026, the tubes should have the corresponding vent holes10201, and the access of a measured medium to the inside of said tubes is provided by the inlet holes1024,1025. Thus, said vent holes10201and slits1026are equivalent in their primary purpose. Given that the cross-section may be of any shape (including a circle, ellipse, polygon, etc. or their combinations) and that there may be more than two electrodes1031or1032, it should be apparent to those skilled in the art that the main principle of designing the housing1020says that the housing1020should have sufficient bending stiffness as a whole, provide secure and rigid fixation of the electrodes1031,1032inside the tubes and allow cutting the slit(s)1026. These requirements are most relevant in the case of a large length of the housing1020, since a very long housing1020may bend along its length during operation, which will affect the geometry of the sensitive element formed by the outer surface of the housing1020and electrodes1031,1032placed inside its tubes. Such a change in the geometry leads to a significant decrease in the measurement accuracy and reduces the serviceability of the sensor as a whole. To provide sufficient bending stiffness, the housing1020may optionally be supplemented with at least one stiffener1021. As previously stated, such a stiffener1021extends along the entire length of the housing1020at the point of contact of at least two tubes. This stiffener provides further bending stiffness and prevents undesirable changes in the geometry of the sensitive element. In some cases, for example, as shown inFIG.5,10,11,12,21, the cross-section of the housing1020is shaped to provide sufficient bending stiffness, and no stiffener1021is required. The cross-section of the stiffener1021is also shaped to provide sufficient bending stiffness of the housing1020as a whole. As an example,FIG.8,14,16,17,19,20show some cross-sections of the stiffener1021that differ from a circle.

The sensitive element of the sensor100is formed by placing the electrodes1031and1032in the housing1020, which thus form several capacitive measuring channels, one of which is the main channel, and the rest are compensation channels. The electrodes1031and1032are identical in their parameters, in particular, they have the same unit-length capacitance, but they differ in their length. The electrode1031is main and mostly as long as the housing1020, while the electrode(s)1032are compensatory and shorter, in particular, but not limited to, much shorter than the electrode1031. Preferably, the electrodes1031,1032are rigidly fixed inside the corresponding tubes of the housing1020. In some cases, the electrodes1031,1032may be secured by stringing spacer rings1033on them. These spacer rings protrude at their edges, so they at least partially form a stop to the tube wall and at least partially secure the ring with the protrusion in the slit1026. Said spacer rings1033are preferably placed in such a way as to provide the best alignment of the electrode1031or1032inside the corresponding tube of the housing1020. At the same time, it should be apparent to those skilled in the art that depending on the length of the electrodes1031,1032, either one spacer ring1033(if the electrode is short, as for the electrodes1032) or several spacer rings1033(if the electrode is long, as for the electrode1031) may be used to provide its rigid fixation inside the tube of the housing1020. At the same time, it should be assumed that the number of spacer rings1033should minimally affect the measurement accuracy, but fix the electrodes1031,1032inside the tubes of the housing1020rigidly enough to maintain the stable geometry of the sensitive element of the sensor100.

Said electrodes1031,1032are tubes made of a metal. If the sensor100is used for level measurements and one of the measured media is a dielectric liquid, for example, not limited to kerosene, gasoline, other fuels, then the electrodes1031,1032do not require further improvements. However, if the sensor100is used for level measurements and one of the measured media is a conducting liquid, for example, not limited to water, then the electrodes1031,1032are further provided with an insulation wrap along their entire length, such as, for example, not limited to a fluoroplastic sheath.

The measuring channels are connected to the input of the computing unit1060by means of threaded metal rods1050, on which expansion sleeves1040preferably made of a dielectric material are screwed as shown inFIG.2. The expansion sleeves1040may optionally have sealing rings1041. The upper part of the expansion sleeves1040is threaded, and this allows a thread joint between said expansion sleeves and threaded holes in the flat part1011of the base1010. Nevertheless, it should be assumed that the connection between the electrodes1031,1032, and computing unit1060must be sealed, and it should be apparent to those skilled in the art that only a particular implementation of such a connection is demonstrated above. On the side of the recess1013(and, accordingly, on the side of the computing unit1060), the metal rods1050, which are thus extensions of the electrodes1031,1032, are electrically connected to the input of the computing unit1060by installing and fixing the electrodes1031,1032in the expansion sleeves1040by means of, for example, not limited to nuts, split washers or a thread-locking fluid.

The length of the housing1020can be significantly increased with the coupling sleeve1028(FIG.22), which is a cylinder that follows the shape of the cross-section of the housing1020preferably in its cross-section or at least the general cross-section of holes in its base and has coaxial slits10281in its side, which are cut mostly along the entire height of the coupling sleeve and span a larger area of the lateral surface. Thus, it should be assumed that such a coupling sleeve1028minimally affects the general geometry of the sensitive element of the sensor100, especially since said coupling sleeve is much shorter than the housing1020. At the same time, those portions of the coupling sleeve1028side that do not have the slits10281are designed in such a way that when connected to the housing1020, the slits1026of the housing1020are not obstructed if they are in the housing1020. The coupling sleeve1028is designed to securely and rigidly connect the two housings1020, which are identical in their geometry and optionally in their length, to each other. For the electrode1031(and the electrode1032, if necessary), two parts of the electrode1031are connected to each other by means of a metal rod1029, for example, not limited to a metal rod similar to the metal rod1050, with similar fasteners. The coupling1028is connected to the corresponding parts of the housing1020, for example, without limitation, by means of clamping screws10282.

Preferably, although not necessarily, the electrodes1031,1032, housing1020, coupling sleeve1028, and connecting rods1050are made of the same material.

The computing unit1060is used to generate a magnetic field in the sensitive element of the sensor100and to convert the received analog signal into a digital signal, which can be transmitted to a visualization unit or a liquid flow monitoring system. As shown inFIGS.23and24, the computing unit1060most typically comprises an analog part1061and a digital part1062. The analog part1061most typically comprises an RC generator formed by resistors and capacitors of the measuring channels1031,1032, an optional capacitive galvanic insulator formed by capacitors C1, C3and designed for protection against a short circuit at the input of the computing unit1060for cases where the measured medium is flammable, an analog key10611designed to switch between the measuring channels1031,1032, therewith a larger number of inputs of the analog key10611and, respectively, further capacitors to provide further capacitive galvanic insulators may be provided depending on the number of the measuring channels, a comparator10612designed to detect frequency pulses coming from the RC generator and having a higher amplitude than a certain preset threshold voltage and to calculate them subsequently, a reference voltage source10613designed to provide a stable reference voltage, an optional rectangular pulse generator10614designed to equalize non-rectangular pulses detected by the comparator, and a galvanic insulator10615(of capacitive or inductive type) designed for protection against a short circuit at the output of the analog part1061of the computing unit1060for cases where the measured medium is flammable. The digital part1062most typically comprises a microcontroller10621connected to non-volatile memory10622, a crystal oscillator10623, and an interface10624, for example, not limited to an RS-485 interface. At the same time, it should be apparent to those skilled in the art that the non-volatile memory, interface, and crystal oscillator may be either independent electronic components or components that are part of the microcontroller as such. At the same time, as can be seen fromFIGS.23and24, as an example, but not a limitation, the galvanic insulator10615may be equipped with filtering power capacitors designed to increase the reliability of the computing unit1060circuit. In turn, as an example, but not a limitation, the connection circuit of the non-volatile memory10622may comprise a resistor to provide the selection of the operating mode and a filtering power capacitor designed to increase the reliability of operation. In turn, as an example, but not a limitation, the crystal oscillator10623may comprise a binding tie formed by impedance-equalizing resistors designed to provide the frequency stability of the crystal oscillator of capacitors. In turn, as an example, but not a limitation, the interface10624at the input of the computing unit1060circuit may comprise resistors for protection against electrostatic and conductive interference, equipped with suppressors (protective diodes) designed for protection against electrostatic discharges and conductive interference of large amplitude.

The digital signal generated by the computing unit1060during measurements is transmitted via the output cable1063to a visualization unit for displaying the current measurements and/or a liquid flow monitoring system. As shown inFIG.25, such a liquid flow monitoring system200may most typically comprise one or more sensors100and a server200. In this case, the sensors100are connected to a transceiver101or a plurality of transceivers101providing a wired or wireless or combined connection of the sensors100to the server200. Such a transceiver is configured to transmit information coming from the output cable1063of the sensor100to the server200. In some cases, such a transceiver101may be equipped with navigation equipment to further transmit information about the location of the corresponding sensor100to the server. In turn, the server200, which is most typically a computer device comprising a processor, memory, and optionally input/output devices, is configured to receive information from the corresponding transceivers101, process it, and provide information about the status and/or location of each sensor100, including through a web interface.

FIGS.26to29show exemplary ways of placing the sensor(s)100in a reservoir300with a measured medium. Such a reservoir300may be any suitable container, such as, but not limited to a canister, including a fuel canister, a tank, including a fuel tank or a rocket fuel tank, a tank vehicle, including a road tank vehicle or a rail tank car, a reservoir, including a tanker tank or an underground tank, etc. The upper wall of a suitable reservoir is at least partially solid. The sensor100is rigidly mounted on the base1010in this solid part so that the sensitive element (the housing1020with the electrodes1031,1032) is vertically oriented and is located mostly in the central part of the reservoir300. To provide sufficient measurement accuracy, the reservoir300may contain several sensors100(FIG.27) depending on the reservoir300dimensions. Aside from this, the housing1020is extended by means of a similar housing through the coupling sleeve1028(FIG.29) depending on the reservoir300geometry. Aside from this, when using several sensors100in one reservoir300of a mostly constant perimeter geometry (FIG.27), it is preferable to place the sensors100in opposite corners of the reservoir. Aside from this, when using several sensors100in one reservoir300of an inconstant perimeter geometry, e.g. with different heights in its different portions (FIG.28), it is preferable to place the sensors100in the center of each such portion as if only one sensor100is placed in one reservoir300of a mostly constant geometry.

As shown inFIG.30, it is preferable to assemble the sensor100by a method400for assembling as follows. At step401, the expansion sleeves1040connected to the metal rods1050are connected to the base1010by means of said threaded holes. Then, at step402, the computing unit1060is installed in the recess1013. Then, at step403, the output cable1063is soldered to the computing unit1060. After that, at step404, the cover1014is installed to protect the recess1013, this is followed by sealing with a compound through the threaded hole1015. After that, at step405, the output cable1063is screwed into the threaded hole1015. Once the compound has cured enough, at step406, pre-calibration is carried out, and the pre-calibration consists of normalizing the values obtained from the compensation measuring channels, which are one or more channels formed by one or more of the metal rods1050at this step, by the value obtained from the main measuring channel, which is the only channel formed by only one metal rod1050at this step, calculating correction factors and recording them into the non-volatile memory of the computing unit1060. Then, at step407, the electrodes1031and1032are screwed onto the metal rods1050, thereby providing their primary connection to the computing unit1060. Now, at step4071, the electrodes1031,1032may optionally be insulated. After that, at step408, the housing1020is installed by stringing it on the electrodes1031,1032and rigidly fixed in the collar part1012of the base1010by means of, for example, not limited to pop rivets, while the electrodes1031,1032are rigidly fixed inside the tubes of the housing1020by means of spacer rings1033.

As shown inFIG.31, it is preferable to pre-calibrate the sensor100at step406as follows.

At step4061, the capacitance of the main measuring channel is measured.

At optional step40611, to obtain the normalized capacitance value of the main measuring channel, the measured capacitance value of the main measuring channel is normalized by the capacitance value at the reference temperature by means of the microcontroller of the computing unit1060by using the temperature compensation factor, the value of which has previously been recorded into the non-volatile memory of the computing unit1060.

At step4062, the capacitance of each compensation measuring channel is measured.

At optional step40621, to obtain the normalized capacitance value of the compensation measuring channel, the measured capacitance value of each compensation measuring channel is normalized by the capacitance value at the reference temperature by means of the microcontroller of the computing unit1060by using the temperature compensation factor, the value of which has previously been recorded into the non-volatile memory of the computing unit1060.

At step4063, to obtain values of primary correction factors, the differences between each (normalized) capacitance value of the compensation measuring channel and the (normalized) capacitance value of the main measuring channel are calculated by means of the microcontroller of the computing unit1060.

At step4064, to obtain a set of primary correction factors, the operations of steps4061to4063are iteratively repeated for a certain period, which preferably does not exceed 30 minutes.

At step4065, to obtain the value of the average correction factor, this value is calculated based on the primary values of the correction factors from the set of primary values of the correction factors by means of the microcontroller of the computing unit1060, and the resulting averaged value of the correction factor is recorded into the non-volatile memory of the computing unit1060of the sensor100.

As shown inFIG.32, it is preferable to measure the level by a method500for level measuring as follows.

At step501, the sensor100is calibrated as follows.

At step5011, the sensor100is installed in a reservoir that does not contain any measured medium.

At step5012, the capacitance values of the main measuring channel and each compensation measuring channel of the sensor100are measured for the reservoir that does not contain any measured medium, therewith each measurement of the capacitance value of each compensation measuring channel is carried out taking into account the average correction factor, the value of which is stored in the non-volatile memory of the computing unit1060.

At optional step50121, to obtain normalized capacitance values of the measuring channels for the reservoir that does not contain any measured medium, the capacitance values of the measuring channels measured at step5012are normalized by the capacitance values of the measuring channels at the reference temperature by means of the microcontroller of the computing unit1060by using the temperature compensation factor, the value of which has previously been recorded into the non-volatile memory of the computing unit1060.

At step5013, the reservoir is filled with a measured reference medium to the maximum permissible level for this reservoir.

At step5014, the capacitance values of the main measuring channel and each compensation measuring channel of the sensor100are measured for the reservoir that contains the measured reference medium, therewith each measurement of the capacitance value of each compensation measuring channel is carried out taking into account the average correction factor, the value of which is stored in the non-volatile memory of the computing unit1060.

At optional step50141, to obtain normalized capacitance values of the measuring channels for the reservoir that contains the measured reference medium, the capacitance values of the measuring channels measured at step5014are normalized by the capacitance values of the measuring channels at the reference temperature by means of the microcontroller of the computing unit1060by using the temperature compensation factor, the value of which has previously been recorded into the non-volatile memory of the computing unit1060.

At step5015, based on the values obtained at steps5012and5014or based on the normalized values obtained at steps50121and50141, calibration values of the capacitance difference are calculated by means of the microcontroller of the computing unit1060by using each capacitance value of the compensation measuring channel obtained at steps5012and5014and the capacitance value of the main measuring channel obtained at steps5012and5014pairwise or by using each normalized capacitance value of the compensation measuring channel obtained at steps50121and50141and the normalized capacitance value of the main measuring channel obtained at steps50121and50141pairwise, and the resulting calibration values of the capacitance difference are recorded into the non-volatile memory of the computing unit1060.

At step5016, which may precede step5015or be carried out in parallel to step5015, based on the values obtained at steps5012and5014or based on the normalized values obtained at steps50121and50141, a dynamic level range is calculated by means of the microcontroller of the computing unit1060, with the dynamic level range being the difference between the capacitance value of the main measuring channel for the full reservoir and the capacitance value of the main measuring channel for the empty reservoir, and the resulting values of the dynamic level range are recorded into the non-volatile memory of the computing unit1060.

At step502, the level is measured by means of the sensor100calibrated at step501as follows.

At step5021, a reservoir is filled with a measured medium to the level at which the longest compensation channel of the sensor100is at least partially immersed in the measured medium, while the measured medium differs from the reference medium; or a reservoir is filled with a measured reference medium to any permissible level for this reservoir.

At step5022, the capacitance values of the main measuring channel and each compensation measuring channel of the sensor100are measured for the reservoir that contains the measured medium, therewith each measurement of the capacitance value of each compensation measuring channel is carried out taking into account the average correction factor, the value of which is stored in the non-volatile memory of the computing unit1060.

At optional step50221, to obtain normalized capacitance values of the measuring channels for the reservoir that contains the measured medium, the capacitance values of the measuring channels measured at step5022are normalized by the capacitance values of the measuring channels at the reference temperature by means of the microcontroller of the computing unit1060by using the temperature compensation factor, the value of which has previously been recorded into the non-volatile memory of the computing unit1060.

At step5023, to obtain values of the capacitance difference, the values of the capacitance difference are calculated by means of the microcontroller of the computing unit1060by using each capacitance value of the compensation measuring channel obtained at step5022and the capacitance value of the main measuring channel obtained at step5022pairwise or by using each normalized capacitance value of the compensation measuring channel obtained at step50221and the normalized capacitance value of the main measuring channel obtained at step50221pairwise.

At step5024, to obtain the value of the correction factor, the values of the capacitance difference obtained at step5023are compared to the calibration values of the capacitance difference, and the ratio between these capacitance differences, which is the correction factor, is calculated by means of the microcontroller of the computing unit1060.

At step5025, to obtain the capacitance value of the level, each capacitance value of the main measuring channel is normalized by the capacitance value of the level by means of the microcontroller of the computing unit1060by using the correction factor, the value of which was obtained at step5024.

At step5026, the resulting values of the level are used by means of the microcontroller of the computing unit1060in order to determine the relative level according to the values of the dynamic range, which are stored in the memory of the computing unit1060.

Obtaining the value of the average correction factor at step4065makes it possible to measure the level of media with a permittivity different from the permittivity of the measured reference medium. Thus, owing to the use of the average correction factor, the capacitive sensor does not require further calibration when the permittivity of the measured medium changes, for example, in case of changes in the fuel type or characteristics.

This disclosure of the embodiment of the claimed invention demonstrates only alternative embodiments and does not limit other embodiments of the claimed invention, since other possible alternative embodiments of the claimed invention, which do not go beyond the scope of the information set out in this application, should be apparent to those routinely skilled in the art, for whom the claimed invention is designed.