RU183097U1 - Improved electrolyte level sensor - Google Patents

Improved electrolyte level sensor Download PDF

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Publication number
RU183097U1
RU183097U1 RU2018101799U RU2018101799U RU183097U1 RU 183097 U1 RU183097 U1 RU 183097U1 RU 2018101799 U RU2018101799 U RU 2018101799U RU 2018101799 U RU2018101799 U RU 2018101799U RU 183097 U1 RU183097 U1 RU 183097U1
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Russia
Prior art keywords
electrolyte
electrodes
sensor
level
measuring
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RU2018101799U
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Russian (ru)
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Евгений Николаевич Коптяев
Евгений Николаевич Попков
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Евгений Николаевич Коптяев
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01FMEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00Indicating or measuring liquid level, or level of fluent solid material, e.g. indicating in terms of volume, indicating by means of an alarm
    • G01F23/22Indicating or measuring liquid level, or level of fluent solid material, e.g. indicating in terms of volume, indicating by means of an alarm by measurement of physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/26Indicating or measuring liquid level, or level of fluent solid material, e.g. indicating in terms of volume, indicating by means of an alarm by measurement of physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields

Abstract

The utility model relates to measuring technique, and is intended to measure the electrolyte level in battery cells, and can be used in parameter monitoring systems of said batteries to simplify maintenance. A capacitive electrolyte level sensor, comprising a sensor housing made entirely of a dielectric resistant to aggressive media, and measuring electrodes placed inside it, characterized in that the housing has an electrolyte slot in the lower part having trapezoidal bends of its longitudinal plane on the side walls slots are located mentioned electrodes. The technical result of the proposed solution is to increase the capacity, which leads to an increase in the sensitivity of the sensor. 4 ill.

Description

The technical field to which the utility model belongs. The utility model relates to measuring technique and is intended to measure the level of electrolyte in battery cells.

The level of technology. Known capacitive sensor of the fuel meter [USSR copyright certificate for invention No. 724932], which is a capacitor, the lining of which is the outer and inner electrodes (pipes), reinforced relative to each other by labyrinth configuration bushings. Voltage is applied to the capacitor plates, and a change in the capacitor capacitance is proportional to a change in the liquid level in the tank.

The disadvantage of this solution is the use of metal electrodes in direct contact with the medium to be measured, leading to the oxidation of the surface of the said electrodes and their gradual destruction, which reduces the life of the sensor.

Also known is a capacitive level sensor [RF patent for invention No. 2112931], containing electrodes electrically isolated from each other — located on a screen made in the form of bushings connected by a pipe. One of the bushings is located at the ends of the electrodes, electrically isolated from it, and the pipe is placed in the cavity of the inner electrode. From the side of the end connected to the measuring circuit, the electrodes are fixed to another sleeve by means of screws and nuts, and are also electrically isolated from it. The electrodes and the screen tube along the entire length are fixed relative to each other by insulating bosses located in the gaps between them.

The disadvantages of this solution include the use of metal electrodes that are in direct contact with the medium to be measured, leading to the oxidation of the surface of the said electrodes and their gradual destruction, which reduces the life of the sensor. It should be noted the complex construction of electrode mounts on electrically insulated bushings - which impairs the measurement accuracy due to technological deviations during assembly. Also, the inner shield of the electrodes must be grounded to ensure a decrease in the edge effect, which is unacceptable in the case of measuring the electrolyte level in the battery cells, since it leads to a decrease in the insulation resistance in their power circuits below the permissible value.

Disclosure of a utility model.

In industrial group lead-acid batteries, an aqueous solution of sulfuric acid (H 2 SO 4 ) is used as the electrolyte. A lead-acid battery is a chemical current source in which electrical energy is accumulated in the form of chemical energy during a charge process, and then, during a discharge, chemical energy is converted into electrical energy.

Used in industry, and especially in shipbuilding, batteries consist of 112 working batteries (cells). They are designed to power consumers of a direct current network, as well as to provide backup power to critical consumers of a power network. A view of one element is shown in figure 1.

The cover of the aforementioned battery cell is made of fiberglass and has the form of a rectangular plate with holes for 12 current leads, a fitting for mechanical mixing of the electrolyte, four fittings of the refrigerator, level sensors and temperature of the electrolyte. In addition, in the middle of the lid there is one threaded hole (filling hole), designed to fill the electrolyte or topping up water into the battery and the exit of gases from the battery. This hole is permanently covered by a ventilation plug.

The battery cell is equipped with a system of mechanical mixing of the electrolyte, which consists of two tubes of a special profile. These tubes are connected by means of a sleeve to a fitting fixed to the battery cover. Air is supplied through the nozzle, which, moving along the tubes, mixes the electrolyte.

Thus, the battery cells are a complex system that requires maintenance and monitoring parameters. One of the most important parameters is the level of electrolyte in the cells, which can fluctuate during operation, and require topping up to ensure the technical characteristics of the battery.

Despite the fact that lead-acid batteries have a number of drawbacks and are difficult to maintain, they are unconditionally used as energy storage due to their low cost and availability for mass production [1]. Improvement of technologies, both production and management during operation, made it possible to neutralize the influence of most negative factors.

Battery management during operation, first of all, includes monitoring and measuring various physical characteristics of the battery in order to determine its current state, and includes considering several characteristics at once within a given range. Both control and measurement are used to maintain the characteristics of the battery cells in the safe operating ranges specified by the manufacturer.

Batteries can be supplied with a monitoring and diagnostic system. A set of monitoring and diagnostic system can provide control over the operation of the entire battery, which includes one or two groups of 112 batteries in each group. The control system provides multifunctional control of the battery parameters, and in particular - measurement of the electrolyte level in the battery cells.

The electrical characteristics of commercial industrial batteries in accordance with the technical conditions are provided at an average electrolyte temperature of 30 ° C, an initial electrolyte density (1.290 ± 0.005) g / cm 3 , an electrolyte level (73 ± 2) mm above the insulator and a working mechanical mixing system.

The electrolyte level depends on many operational parameters, including temperature. With a decrease or increase in the temperature of the electrolyte, its level accordingly decreases or rises by 3 mm for every 5 ° С. Also, the electrolyte level may decrease during active use due to evaporation. The mentioned parameters - temperature and electrolyte level, can be measured by various systems for monitoring and diagnosing batteries [1, 2], which include electrolyte level sensors.

In the prior art, various versions of level sensors for liquids and bulk solids, in particular of a capacitive type, are known. The main difference between the capacitive type of sensors is the continuous nature of measuring the level of liquids, which distinguishes it from some other level sensors produced by the industry - having several discrete values corresponding to level ranges.

The basis of the principle of operation of capacitive level sensors is the presence of the electric capacitance of a capacitor formed by measuring electrodes and a measured medium between them - as is known from the literature on the basics of electrical engineering [3]. If two conductive bodies (electrodes) are separated by a dielectric and carry opposite electric charges, then an electric field is created in the space between them. Under the capacitance between the electrodes understand the absolute value of the ratio of charge to voltage between the bodies. In general, any two conductive bodies separated by a dielectric have an electrical capacitance.

An important characteristic of the medium between the electrodes of the electric capacitance is the relative dielectric constant of the medium, which characterizes its properties. Technically, the dielectric constant of the medium determines the absolute value of the electric capacitance, which is directly proportional to the value of the said dielectric constant. Thus, when using a liquid medium between the electrodes, the capacitance increases in proportion to the increase in the dielectric constant of the medium.

If there are two media between the electrodes of the electric capacitance, the total capacitance can be represented as the sum of separate capacitors connected in parallel with different capacities.

When measuring the electrolyte level, there are two media: air with a dielectric constant close to 1 - and a solution of sulfuric acid having a dielectric constant close to 100, which is known from the relevant literature [3]. Thus, the dielectric constant of the media differs by two orders of magnitude (100 times), and with sufficient accuracy for practical purposes, we can assume that the total capacitance of the measuring electrodes of the sensor is determined mainly by the electrolyte level, and the upper part filled with air practically does not participate in the formation capacities.

Thus, the dependence of the capacitance of the measuring electrodes will be proportional to the current level of electrolyte in the battery cell. The most convenient way to measure the electrolyte level is as shown in figure 2. The sensor case in this case is made of a dielectric resistant to aggressive media, and has a through flat slot in the lower part (in contact with the electrolyte), on the walls of which there are measuring electrodes that do not have direct contact with the electrolyte.

The sensor shown in figure 2 is mounted on the cover of the battery cell, and partially immersed in the electrolyte. Thus, with fluctuations in the electrolyte level, the level in the slot of the sensor housing will change - and in proportion to it, the capacitance of the measuring electrodes will change.

However, the aforementioned version of the electrolyte level sensor is characterized by a small capacitance of the measuring electrodes located inside the housing. This is explained by the relatively large gap between the electrodes and their limited area, which complicates the measurements and reduces the sensitivity of the sensor to fluctuations in the electrolyte level, and also increases the influence of the noise level of the measuring circuits on the accuracy class of the measurements performed in this way. In addition, the use of a through slot means a low utilization rate of the volume of the level sensor housing (i.e., low efficiency).

The claimed solution proposes to eliminate the mentioned disadvantages of the electrolyte sensor, namely, to increase the capacitance between the electrodes by increasing their area.

Figure 3 shows a cross-section of the electrolyte level sensor shown in figure 2, and having a limited area of the electrodes through the slots in the housing.

As a solution to the problem, it is proposed to use the cross-section of the improved level sensor shown in figure 4. This design has the following advantages: increased capacitance between the electrodes, which increases the sensitivity to fluctuations in the electrolyte level and measurement accuracy, as well as a higher utilization rate of the sensor housing volume, which increases the efficiency of the solution and allows to reduce dimensions.

In the proposed solution, a multiple (up to tens of times) increase in the capacity of the measuring electrodes is possible, which is an undoubted technical advantage. The trapezoidal shape of the slot for the electrolyte allows not only to increase the area of the measuring electrodes and their capacity, but also to more effectively use the cross-sectional area of the sensor housing - especially in the case of using a rounded outer shape of the sensor housing.

The presented solution is simple and therefore industrially applicable - allowing to achieve improvement of a number of technical characteristics of the selected prototype. The use of a housing made of a resistant dielectric protects the measuring electrodes from the effects of an aggressive environment (sulfuric acid solution - battery electrolyte), and the characteristic of the dependence of capacity on the electrolyte level is almost proportional.

The proposed technical solution is new, having the following fundamental differences from the prototype:

- measuring electrodes are located inside the sensor housing made of a dielectric (plastic) resistant to aggressive media, which eliminates the gradual destruction of the mentioned electrodes by the aggressive electrolyte medium;

- flat electrodes are located on the walls of the sensor housing, which simplifies the design and avoids complex types of mounting, especially in comparison with the selected prototype;

- the design of the electrodes does not have the "end effect" of the parasitic capacitance of the cylindrical electrodes, affecting the accuracy of the measurements - characteristic of the solution chosen for the main prototype;

- trapezoidal bends of the longitudinal plane of the slot of the sensor housing provide a large length of the aforementioned slot, which leads to an increase in the area of the measuring electrodes and an increase in the capacitance of the capacitor formed by them.

Thus, the set of essential features of the utility model leads to a new technical result - an increase in the capacitance of the measuring capacitor electrodes and a proportional increase in sensitivity.

A brief description of the drawings. The figure 1 shows the appearance of the battery cell. Here 1 - holes for electrolyte level sensors, 2 - plug, 3 - current output, 4 - fitting for water cooling system, 5 - fitting for mechanical electrolyte mixing system. The figure 2 shows the electrolyte level sensor. Here 6 is the sensor housing, 7 is the measuring electrode. Figure 3 shows a cross section of an electrolyte level sensor. Here 6 is the sensor housing, 7 is the measuring electrode. Figure 4 shows a cross section of an improved electrolyte level sensor. Here 6 is the sensor housing, 7 is the measuring electrode.

List of used literature.

1. Brussili M., Pistoia J. Industrial use of batteries: from cars to the aerospace industry and energy storage. M .: Technosphere, 2011 .-- 784 p.

2. Pavlyukov V.M., Tsvetkov A.A., Krotenko A.V., Temirev A.P., Kiselev V.I., Khamizov P.P., Manovitsky A.M., Batyuchenko I.L. Automated system for monitoring and diagnostics of ship-based batteries. RF patent for the invention No. 2474832.

3. Bessonov L.A. Theoretical foundations of electrical engineering. M .: Higher school, 1973.- 752 p.

Claims (1)

  1. A capacitive electrolyte level sensor, comprising a sensor housing made entirely of a dielectric resistant to aggressive media, and measuring electrodes placed inside it, characterized in that the housing has an electrolyte slot in the lower part having trapezoidal bends of its longitudinal plane on the side walls slots are located mentioned electrodes.
RU2018101799U 2018-01-17 2018-01-17 Improved electrolyte level sensor RU183097U1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU1758441A1 (en) * 1990-02-05 1992-08-30 Харьковский Электромеханический Завод "Элеватормельмаш" Capacitive level indicator
RU2087873C1 (en) * 1994-12-19 1997-08-20 Николай Дмитриевич Куликов Electric capacitive converter for level measurement
EP1462775B1 (en) * 2003-03-25 2007-12-05 ELTEK S.p.A. Device for detecting physical variables of lubricating oil of an internal combustion engine
GB2509143A (en) * 2012-12-21 2014-06-25 Cambridge Consultants Capacitive fluid level sensor
RU2619314C1 (en) * 2016-06-20 2017-05-15 Андрей Николаевич Алексеев Method of level sensor implementation

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU1758441A1 (en) * 1990-02-05 1992-08-30 Харьковский Электромеханический Завод "Элеватормельмаш" Capacitive level indicator
RU2087873C1 (en) * 1994-12-19 1997-08-20 Николай Дмитриевич Куликов Electric capacitive converter for level measurement
EP1462775B1 (en) * 2003-03-25 2007-12-05 ELTEK S.p.A. Device for detecting physical variables of lubricating oil of an internal combustion engine
GB2509143A (en) * 2012-12-21 2014-06-25 Cambridge Consultants Capacitive fluid level sensor
RU2619314C1 (en) * 2016-06-20 2017-05-15 Андрей Николаевич Алексеев Method of level sensor implementation

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MM9K Utility model has become invalid (non-payment of fees)

Effective date: 20181024