RU2251705C2 - Device for measuring permittivity of dielectrics - Google Patents

Abstract

FIELD: measuring engineering.

SUBSTANCE: device comprises indication unit, electronic measuring unit, sensor, and control members. The indication unit and measuring electronic unit are mounted in a single housing. The sensor is a cylindrical plate-type capacitor.

EFFECT: enhanced accuracy of measuring.

6 cl, 4 dwg

Description

The invention relates to measuring equipment and can be used in industry for measuring and monitoring the dielectric constant (constant) of liquid and gaseous dielectric media, for example, in oil refineries, oil depots, as well as in operational measurement and control systems, in particular in field conditions (such as express method), in the retail sale of petroleum products, at gas stations, individually by motorists and in various kinds of technological processes.

A measuring device for studying the dielectric parameters of liquid and solid samples is known, comprising a stepwise coaxial junction connected to a hollow short-circuiting element connected to a source of thermostabilizing liquid, a high-frequency connector, an insulating washer and fittings (USSR author's certificate, No. 1698831 A1, IPC: G 01 R 27/26, 10/31/1989).

Known portable device for monitoring the quality of fuel, containing a drain hose, at one end of which there is a tip for connecting to the fuel tank of the machine and sampling fuel, a transparent housing, a fitting installed on the other end of the drain hose and connected to the inlet valve located on the bottom cover a transparent case, three chambers communicating with each other, mounted inside a transparent case, in the first of which is an oil densimeter, in the second - a hydrometer, and the third camera inspection (certificate for a utility model №0003827, G 01 R 33/22, 9/14, 23.08.95).

A device is known for measuring technical characteristics (including measuring the dielectric constant parameter) of dielectric media, for example, liquid fuel in a working vessel, containing a radiation source and receiver, optically coupled reflective prisms with a gap between them, two adjacent hollow tubes, to the ends of one of which reflective prisms are attached, and the ends of the other tube are paired with a radiation source and receiver, in addition, the device contains an indicator and a screen with calibrated holes Voith corresponding to transmission maxima reference fuel grades (Certificate for useful model №0006630, G 01 N 33/22 from 05/16/98).

All of the above devices have common significant disadvantages, the main of which are the influence of pickups on their operation, as well as the fact that when using devices operating with microwave radiation, there is a distortion in the measurement of parameters, in particular, a decrease in the accuracy of their measurement associated with the influence of radiation on the properties of the investigated dielectric media, and the resulting parameter measurements and error indicators are unstable in time. In addition, basically all of these devices are large-sized and, as practice has shown, their use is limited.

The closest analogue to the claimed device and adopted as a prototype is a known device for measuring the dielectric constant of dielectric media, which is described in the method of non-contact measurement of the dielectric constant of a dielectric substance, protected by RF patent No. 21115935 C1, G 01 R 27/26, G 01 F 23/26, priority: 04/16/1992

The known device for measuring the dielectric constant of dielectric media contains a sensor, measuring electronic means and an indication unit, control means, the sensor includes two parallel overlapping conductive plates electrically isolated from each other, to which an alternating voltage of high frequency is applied. The sensor works on the principle of a capacitor.

The specified device has all the disadvantages of the above analogues. In addition, the disadvantages of this device are the inability to measure the dielectric constant of gaseous media; it works only in stationary mode (it is non-portable) and it is not possible to use it in express analyzes; in practice, the device is used only for measurement, as for the control of the specified parameter, this process is technically impossible, since it does not have high measurement accuracy, and besides, it works only in stationary mode.

The main objectives of the claimed technical solution of the device for measuring the dielectric constant of dielectric media are:

- achieving a high degree of measurement accuracy at an optimally low radiation frequency;

- reduction of interference levels;

- achieving stability and improving the quality of output signals with the possibility of not only measuring the dielectric constant, but also its control;

- the possibility of using the device for a wide range of dielectric media, namely for liquid and gaseous media.

Other objectives of the claimed invention: to make the device complex, small-sized (“pocket”), which will make it possible to use it quickly (in express analyzes) in the field, in addition, the tasks are the simplicity of technical performance, the availability of goods for a wide range of consumers and the achievement of enough high design solutions.

The essence of the claimed device.

A device for measuring the dielectric constant of dielectric media is made in the form of a monoblock containing an indication unit 1 (Figs. 1, 3, 4), a measuring electronic unit 2 (Figs. 1, 4), mounted in one housing 3, sensor 4, controls, including a power switch 5, a switch of the kind of work (toggle switch) 6 and a regulator for calibrating the dielectric constant of various samples of petroleum products 7, while the sensor 4 is a cylindrical plate capacitor, which includes a cylindrical body 8, having the base of the hole 9 for the input of the measured medium and through holes 10 for the exit of air on the side surface, in its upper part, inside of which are installed a gap with a cylindrical cup 11 and a cylindrical stand 12, which has a curved surface in the lower part, on the inside, and the upper part, from the outside, - the stop 13, formed by the difference in the outer diameters of the rack 12, while the sensor contains a dielectric ring 14 having the shape of a cylinder in the upper part and the shape of a truncated cone and which is installed the lower base on the stop 13 and at the level of the through holes 10 of the housing 8, the Central three-stage rod 15 having different diameters in height, forming a stop 16 in the upper part of the rod and connected to the cylindrical glass 11 by means of a crosspiece 17. The sensor also contains an insulating sleeve 18 installed in the upper part of the body and the lower part resting on the stop 16 of the rod 15. The middle part of the rod 15 is installed with a gap in relation to the rack 12, and there are voids between its lower part and the lower part of the rack 12. In addition, the diameter of the middle part of the rod 15 is 1.5 times the diameter of its upper part and 2 times the diameter of the lower.

All composite elements of the claimed device are structurally (mechanically and electrically) technologically and functionally interconnected.

The claimed device is illustrated by the following drawings. Figure 1 presents a General view of the device, front view (photo after scanning it); figure 2 presents a block diagram of a device; figure 3 - sensor device in accordance with the invention, in section and figure 4 - sensor device in accordance with the invention, bottom view (photo after scanning).

A General view of the device for measuring and controlling the dielectric constant of dielectric media is presented in figure 1, its front view. The device is a monoblock including a display unit (digital indicator showing the value of the measured parameter) 1, a measuring electronic unit (IED) 2 mounted in the housing 3, and the sensor 4. The housing 3 is made in the form of a flat elongated parallelepiped.

In addition, the device (figure 1) has controls including a power switch 5, a switch of the kind of work (toggle switch) 6 and a regulator 7 for calibrating the dielectric constant (constant) of various samples of oil products.

The design solution of the device is made in such a way that it is convenient to maintain and operate, in particular, the housing 3 has a “soft”, rounded design with rounded edges and corners, and stiffening ribs are made on its lateral surfaces, which make it convenient to hold the device in hand with it use.

Figure 2 presents a block diagram of the claimed device. The block diagram includes the following blocks: an indication block (pos. 1), a measuring electronic unit (IEB) (pos. 2), and a sensor (pos. 4). In turn, the IEB includes a scaling and adjustment scheme; precision crystal oscillator; input signal processing circuit; input bi-directional differential amplifier and switching unit. The block diagram of the device and the circuit of the IEB with its elements are presented only to explain the claimed device.

The sensor 4 (FIG. 3) of the claimed device comprises a cylindrical body 8 with an opening 9 in the base and through holes 10 in the upper part, a cylindrical cup 11 mounted inside the body, a cylindrical stand 12 with a stop 13, a ring 14 in contact with the body 8 and with a stop 13 racks 12, the Central rod 15 with emphasis 16, the crosspiece 17 and the sleeve 18.

The device operates as follows.

The claimed device is electronic, automated, designed to measure and control by direct express method of comprehensive matching of the composition of the fractions of the measured oil products, viscosity up to 10 centistokes, its control sample by dielectric constant. The device allows you to control petroleum products (gasoline of any brand, diesel fuel and other hydrocarbon products) for compliance (identity) with the reference sample, by the dielectric constant of the tested petroleum products, such as "HEPTAN". The numerical values of the measured values are read directly on the instrument panel (digital indicator) in arbitrary units.

Before measuring, carry out the following. Turn on the power supply of the device in the network (220 V). On the front panel of the housing 3 (Fig. 1), the power switch 5 is turned on (position: “ON”). Toggle switch 6 (type of work switch) switch to “CONTROL”. Further, holding the device in hand, the sensor 4 of the device is lowered into a container with a capacity of up to 250 ml. In the latter, the GEPTAN reference oil is poured to the level of the through holes 10 of the sensor 4. The liquid enters the device through the opening 9 of the cylindrical body 8 and fills all the gaps and voids of the device between the cylindrical body 8 and the cylindrical glass 11, between the body 8 and the ring 14 between the cylindrical cup 11 and the stand 12, the gap and voids between the cylindrical stand 12 and the rod 15.

Then, without completely removing the sensor 4 from the liquid, the device makes slow movements up and down. With this, the device is washed and air bubbles are removed from it, which can affect the measurement. Next, the device is removed and the remaining fluid is removed from the sensor.

The liquid in the tank is reused to flush the sensor during subsequent calibration of the device.

The sensor 4 of the device is lowered into the second container, in which "HEPTAN" is poured, and the procedure of lowering the sensor into the container and its subsequent dipping is repeated. Then the sensor is lowered into the measured liquid and after 5-10 c the switch of the 6th kind of work (toggle switch) is switched to “MEASUREMENT”. The indicator 1 should display numbers close to 00.0. If the numbers on the scoreboard will differ from the indicator 00.0, then it is necessary to set the controller 00.0 on the scoreboard of the regulator 7 to calibrate the dielectric constant. After that, a measured liquid, for example A76, is poured into a clean container, and the sensor 4 is washed with this gasoline, as mentioned above. Next, the measured liquid is poured into a clean container and a measurement is made, while previously the regulator 7 is switched to “MEASUREMENT”. The numerical values on the scoreboard, expressed in arbitrary units, are the values of the dielectric constant of the measured liquid.

Calibration of the device should be carried out after 4-5 measurements of gasolines. In case of clogging of the sensor, it is washed with acetone. The dielectric constant of gasoline in arbitrary units for different gasolines should be in the following limits: A76-14-28; AI92-30-42; AI95-45-70; AI98-75-110.

After the measurement, the power switch 5 on the panel of the housing 3 is installed on the label: “OTC” and the power supply is disconnected from the network. Food of the device: 9 V 5% (from the battery like "Krona"). Current consumption at a voltage of 9 V 5 mA, technical preparation time, after turning on the device 3-5 s, time for establishing readings 3-5 s, continuous operation time: around the clock (limited only by battery capacity), measurement error 0.5. The minimum volume of gasoline required for measurements is 150 ml. The frequency of the sound range is normalized from 20 Hz - 20 kHz to 100-200 kHz. The level of interference is reduced through the use of low frequency. The sensor is neither a transmitter nor a receiver.

The claimed device is simple to perform, it is compact and convenient to operate. The crosspiece 17, the sleeve 18 and the rod 15 are fasteners, and the stops 13 and 16 are the fixing elements of the ring 14 of the dielectric and the sleeve 18, respectively.

The quality and achievement of stable signals are improved due to the implementation of the device in the form of a monoblock, including an indication unit 1, a measuring electronic unit (IED) 2 and a sensor 4, due to the design solution of the sensor 4 directly, operating on the principle of a plate capacitor, due to the presence and design solution rings made of dielectric material.

An electronic circuit operating at a frequency of 800 Hz, connected to a sensor, gives accurate and stable results of measuring the dielectric constant without interference from external sources of interference. The scale of the device is linear with a constant gain and is configured so that for the bulk of the measured petroleum products is in the range from 0 to 100 cu The measurement time of the dielectric constant of the measured liquid is 3-5 s; the indicator corresponding to the total value of the fractional composition of the measured oil product is displayed on the digital indicator board. Conformity of quality (compliance of fractional compositions) of oil products is determined by the equality of the signal values of the measured and reference sample. The device is sensitive to mixtures of petroleum products, such as high-octane and low-octane gasolines, to various additives mixed with automobile gasolines.

The claimed device can carry out a simplified indicator control of the dielectric constant of oil products. For this, when the device is turned on, the sensor 4 is lowered into the tank, where the control oil product, for example A76 gasoline, is poured to the level of the through holes 10 of the device. Switch 6 is set to the “MEASUREMENT” position. Regulator 7 sets an arbitrary numerical value for the monitored oil product on the digital indicator board 1, for example, 76.0 for A76 gasoline, or 92.0 for AI92 gasoline. Next, the device is rearranged in the compared sample and as a result of measurement on the scoreboard, a numerical indicator is displayed. The coincidence of the measured number with the previously set number will mean that the compared compositions of the oil products have identical dielectric constant fractions.

The claimed device can be made of currently available materials, for example plastic, stainless steel, metallized plastic. The device allows both to measure the dielectric constant, and to control this indicator. The experimental prototypes of the device have been tested in the metrology laboratory with positive results.

Claims (7)

1. A device for measuring the dielectric constant of dielectric media, comprising elements in the form of a display unit, a measuring electronic unit, a sensor, controls, characterized in that the elements of the device are mechanically and electrically interconnected and are a monoblock in which the display unit and the measuring electronic the unit is mounted in one housing, the sensor is a cylindrical plate capacitor, which includes a cylindrical body having a hole in the base for I receive the measured medium, and on the side surface, in the upper part, through holes for air outlet, inside the sensor housing there is a clearance with a cylindrical cup and a cylindrical stand, which has a curved surface in the lower part, on the inside, and in the upper part, with on the outside, there is an emphasis, while the sensor contains a ring having the shape of a cylinder in the upper part and the shape of a truncated cone in the lower part, and which is installed between the sensor housing and the cylindrical rack at the level of through holes, and the lower base it is mounted on the stop of a cylindrical strut, and the sensor includes a central three-stage rod installed with a gap with the strut, connected at the bottom with a cylindrical cup and having different diameters in height, forming a stop in the upper part of the rod, an insulating sleeve mounted in the upper part of the housing and mounted on the rod stop. 2. The device according to claim 1, characterized in that the emphasis of the cylindrical rack is formed by the difference in its outer diameters. 3. The device according to claim 1, characterized in that the ring with the lower base is mounted on the stop of the cylindrical rack. 4. The device according to claim 1, characterized in that the ring is made of a dielectric. 5. The device according to claim 1, characterized in that the central rod is connected to the glass by means of a cross. 6. The device according to claim 1, characterized in that there are voids between the lower part of the rod and the inner curved surface of the rack. 7. The device according to claim 1, characterized in that the diameter of the middle part of the rod is 1.0-1.5 times larger than the diameter of its upper part and 2.0-2.5 times larger than the diameter of the lower.

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