RU2282165C2 - Method and device for determining pressure fluctuations - Google Patents

Abstract

FIELD: measuring technique.

SUBSTANCE: method comprises determining output voltage and transformation ratio of the thin-film capacitive gage as a function of temperature and storing the results in memory. The temperature dependencies of the coefficients of dielectric permeability, flexibility modulus, and output voltage and sizes of the gage plates are obtained from the results of a preliminary experimental study. The device comprises thin-film capacitive gage, charge and voltage amplifiers, switch, units for storing, multiplication, and polarization, and indicator and control unit. The gage is connected with the inputs of the dividing unit, multiplying unit, and memory unit through the charge and voltage amplifiers. The memory unit is connected with the outputs of the units for multiplying and dividing. The other outputs of the units are connected with the indicator. The control unit is connected with the control inputs of the memory unit, units for multiplying and dividing, and switch.

EFFECT: enhanced precision.

2 cl, 4 dwg, 1 tbl

Description

The invention relates to the field of measurement technology and can be used to determine pressure and temperature pulsations in aircraft.

A device for measuring pressure pulsations is known. The device contains thin-film capacitive sensors, a polarization source, charge and voltage amplifiers, protective circuits; the signal from the capacitor plates is fed to the charge amplifier, then to the voltage amplifier and indicator.

Such a device allows the measurement of pressure pulsations on the surface of an object without drainage (see RF patent No. 2087883, “Method for determining pressure pulsations and a capacitive sensor for its implementation”, by A.A. Kazaryan, IPC G 01 L 9/12).

A known method for measuring pressure pulsations on a deformable object. The sensor unit contains the first and second groups of sensing elements (SE) pressure. The first group of sensitive elements remove a signal that carries information from the effects of pressure, product deformation, noise and interference. From the second group of CE pressure pulsations glued directly in the region of maximum deformation of the product, a strain signal is obtained. Then, from the general signal of the first group of SEs, the signal of deformation of the product, the noise of the second group of SEs are isolated and a useful signal is obtained from pressure pulsations.

This method allows you to determine pressure pulsations without draining the product (see RF patent No. 2087883 "Method for determining pressure pulsations and a capacitive pressure sensor for its implementation", by A.A. Kazaryan, IPC G 01 L 9/12).

The disadvantages of the method and device include the inability to take into account the effect of temperature on the measurement results.

Closest to the proposed invention, the technical solution is a device for determining pressure pulsations, containing a high-temperature capacitive sensor with plates and a screen (up to 300 ° C). A sensor with a matching amplifier is connected by a cable with two continuous screens. The device contains a power source for a voltage amplifier and a charge amplifier. To polarize the sensor, a direct current polarization source is provided. A sensor with measuring equipment is matched with a charge amplifier, the signal is fed through a voltage amplifier to a microprocessor.

Such devices do not allow measuring pressure pulsations on the surface of the product without drainage (see RF patent No. 2182321, 2002, "Method for measuring pressure pulsations", by A. A. Kazaryan, IPC G 01 L 9/12).

The disadvantages of the device include the following: for mounting the sensor, it is necessary to drain the product; there is no way to take into account the effect of temperature on the measurement results.

Closest to the proposed invention, the technical solution is a method of measuring pressure pulsations. Under normal conditions, determine the voltage of noise, interference and graduate the sensor. To determine the voltage of thermal noise, the sensor is placed in a calm environment, set the elevated temperature. At rest, the sensor is affected by temperature, and it is isolated from external electromagnetic interference, acoustic background noise, and pressure (P = 0). Then the sensor, together with the cable, is placed in an environment of elevated temperature, the voltage of thermal noise is measured without the influence of pressure pulsations. Separately determine the thermal noise of the sensor and cable. Under normal conditions, after the isolation of the thermal noise voltage and external noise from the common signal, fixed pressure pulsations are fed to the sensor, and the device conversion coefficient is determined. If the operating temperature is unknown, then, taking into account the design features of the sensor, make up its equivalent electrical circuit and based on the thermal noise voltage of the sensor, you can calculate the temperature of the medium. Moreover, the output of the sensor is consistent with the input of the charge amplifier.

After coordination, the signal from the output of the charge amplifier is supplied to the voltage amplifier, normalized and fed to the indicator. Amplifiers of voltage and charge feed a constant current source. The capacitive sensor is also polarized with a constant voltage from the polarization block.

This method allows you to measure pressure pulsations on the surface of the product by drainage (see RF patent No. 2182321, "Method for measuring pressure pulsations", by A. A. Kazaryan, IPC G 01 L 9/12).

The disadvantage of the method of measuring pressure pulsations is the inability to obtain the true value of the pressure signal when the surface temperature of the object changes.

The objective of the present invention is to expand the scope and increase the measurement accuracy by compensating (correcting) the effect of temperature on the measurement results.

The technical result is achieved in that in a device for determining pressure pulsations containing a capacitive sensor, a charge amplifier, a voltage amplifier and a polarization unit, in which the output of the polarization unit is connected to the capacitor plate, and the other capacitor plate is connected to the input of the charge amplifier, the output of which is connected to the input of the voltage amplifier, additionally introduced blocks of memory, division, multiplication, control and a switch that is connected to the signal output of the voltage amplifier, the output of the switch with union of the inputs of the division blocks, multiplication and memory storage unit coupled to the switch and outputs the division and multiplication unit, an output of division blocks, multiplication, and a memory coupled to the indicator and control unit connected to control inputs of memory blocks, multiplication, division, and a switch.

, где Р - пульсации давления, и выходное напряжение U_вых, затем вычисляют температурные зависимости коэффициентов для диэлектрической проницаемости α_ε, модуля упругости α_E и температурного расширения обкладок α_{а, b}, а также выходного напряжения α_U, принимая базовую температуру равной 23°С, все перечисленные зависимости запоминают, из суммы (1-α_{а, b})+(1-α_ε)+(1-α_E)=1-α_U и получают коэффициент выходного напряжения α_U=α_ε+α_E+α_{a, b}-2, все параметры датчика представляют в виде таблицы и регистрируют, затем датчик помещают в среду с известной температурой выше 23°С, подают контролируемое давление P≠0, по известному значению температуры определяют коэффициент выходного напряжения α_U, затем измеряют выходное напряжение U_вых, несущее информацию об изменении давления, это напряжение делят на коэффициент выходного напряжения α_U, получают базовое значение выходного напряжения U_вых23 и коэффициент преобразования датчика

; если в условиях эксплуатации температура датчика неизвестна, то на датчик подают контролируемое давление, градуируют при температуре 23°С, измеряют и запоминают базовое выходное напряжение U_вых23, затем на датчик подают то же давление при повышенной температуре, измеряют выходное напряжение U_вых и делят его на базовое выходное напряжение U_вых23, получая значение коэффициента α_U, по нему вычисляют температуру эксплуатации, причем операции запоминания, деления и умножения осуществляют по управляющим сигналам.The technical result is also achieved by the fact that in the method for determining pressure pulsations, based on the fact that pressure is applied to the capacitive sensor, which is converted into an electrical signal, it is amplified and recorded, then, at rest under normal conditions, the sensor is graduated and noise voltages are determined, then the sensor is placed in a medium of elevated temperature, the voltage of thermal noise is measured at its output, the temperature of the medium is determined, the pressure pulsations are determined, in it before determining the pressure pulsations At rest, the temperature dependences of the dielectric constant ε, the elastic modulus E, and the dimensions of the sensor plates a × b are determined, then the metrological characteristics of the capacitive sensor (with solid or gaseous dielectric) are determined, namely, the capacitance C, the increment of the capacitance ΔС, the sensor conversion coefficient

where P is the pressure pulsation and the output voltage U _o , then the temperature dependences of the coefficients for the dielectric constant α _ε , the elastic modulus α _E and the thermal expansion of the plates α _{a, b} , and the output voltage α _U are calculated, taking the base temperature equal to 23 ° C, all the above dependencies are remembered from the sum of (1-α _{a, b} ) + (1-α _ε ) + (1-α _E ) = 1-α _U and get the output voltage coefficient α _U = α _ε + α _E + α _{a, b} -2, all parameters of the sensor are presented in the form of a table and recorded, then the sensor is placed in an environment with a known temperature Aturi above 23 ° C, is fed, controlled pressure P ≠ 0, the known temperature value determined coefficient α _U output voltage is then measured output voltage U _O, carrying information about a change in pressure, this voltage is divided by the coefficient α _U output voltage obtained base value output voltage U _o23 and sensor conversion coefficient

; if operating conditions of the sensor temperature is unknown, then the sensor is fed controlled pressure, calibrated at 23 ° C, is measured and stored basic output voltage U _vyh23, then the sensor is supplied at the same pressure at elevated temperature, measured output voltage U _O and divide it to the base output voltage U _o23 , receiving the value of the coefficient α _U , the operating temperature is calculated from it, and the operations of memorization, division and multiplication are carried out according to the control signals.

и выходное напряжение датчика U_вых при изменении температуры.Figure 1 shows a block diagram of a device. Figure 2 shows by way of example the dependence of the dielectric constant ε of a PM brand polyimide film on temperature θ (over a wide range) and frequency, pressure pulsations, and figure 3 shows the temperature dependence of the dynamic elastic modulus E. Figure 4 shows the temperature dependence of the coefficients of thermal expansion of the plates α _{a, b} , dielectric constant α _ε , elastic modulus α _E , output voltage α _U. Using these coefficients, it is determined how many times the sensor parameters change, i.e. capacitance C, increment of capacitance ΔC, sensor conversion coefficient

and the output voltage of the sensor U _o when the temperature changes.

The device contains a capacitive pressure sensor 1 with plates 2, a screen 3, a DC polarization unit 4. The output of the sensor through a charge amplifier 5, a normalizing voltage amplifier 6, a switch 7 is connected to the signal inputs of the divisions 8, multiplication 9, memory 11 and indicator 10, moreover, the signal inputs of the memory block 11 are connected to the outputs of the blocks of division and multiplication. Blocks 7, 8, 9, 11 operate under the control of the control unit 12. The outputs of block 12 are connected to the control inputs of the memory blocks 11, multiplication 9, division 8, and switch 7.

The device operates as follows. In a polarized state in the standby mode of the sensor (without pressure pulsations) and in the operating mode (under the influence of pressure), the pressure converted into an electrical signal by sensor 1 carries information about the complete signal, noise and interference, and the useful signal. Then, after matching the sensor signal in the charge amplifier 5 and the normalizing amplifier 6, the signal through the switch 7 is fed to the input of the divisions 8, multiplication 9, and indicator 10. In the memory block 11, at the command of the control unit 12, the output voltage U _o , sensor conversion coefficient, coefficients are stored α _{a, b} , α _ε , α _E , α _U , sizes of the plates a × b. The output voltage dividing unit 8 U _O of the amplifier 6 is divided into coefficient α _U, this value must be multiplied by the base signal U _vyh23 obtained at an initial reference temperature 23 ° C.

In the multiplication unit 9, at the command of the control unit 12, the output voltage U _o is multiplied by the coefficient α _U.

In the general case, the control unit must enter the parameters of the sensor, output information, organize all types of calculations, and also, if necessary, ensure the conversion of the analog signal to digital.

Domestic charge amplifiers are made on an integrated microcircuit 544UD1. Using a DC negative feedback circuit provides low zero drift. The gain of the charge amplifier is approximately 1. The distance between the sensor and the charge amplifier is 0-50 m. The voltage amplifier, memory, division, and multiplication units are known circuits in electronics. Indication and control units can be computers. The amplification factors of the normalizing voltage amplifier are recommended 50, 100, 1000, 1500, 2000 and polarization with direct current with a voltage of 100 V.

Pressure pulsations (sound pressure) can be continuous, it makes sense to quantize the pressure in time and present it as discrete readings in a particular numerical code. In practice, the device can be implemented both in single-channel and multi-channel (several tens of channels) performance.

The method for determining pressure pulsations is based on the following factors and assumptions.

It is known that existing (including thin-film) sensors have several types of error: temperature; nonlinearity; hysteresis; drift of zero.

Correction (compensation) of hysteresis and drift is not possible. If, nevertheless, an attempt is made to make such an adjustment, then you need to know the physical process, and the computational costs are very high (G. Kovalsky. Compensation of errors of pressure sensors for simple connection with a microphone, VCP, translation No. N-41769, 1987).

The main reason for the errors of thin-film sensors is associated with the influence of temperature θ on the dielectric constant ε, the elastic modulus E, and the size of the sensitive element a × b.

1. Let us evaluate the effect of temperature on dimensions, output voltage, and sensor conversion coefficient. The temperature range is chosen based on the possibility of PM brand polyimide and kapton - from 20 to 300 ° C. Temperature fluctuations affect the elastic modulus E (θ) and the dielectric constant ε (θ); their experimental values are entered into the memory block.

a) We assume that the film is homogeneous and heats evenly. The equations of general deformation along the main axes of the film have the following form: Δa / a = α ₁ θ, Δb / b = α ₂ θ, where α ₁ and α ₂ are the linear expansion coefficients along the width (a) and length (b) of the CE from a polyimide film, if it differs in anisotropy, for example, due to technological drawing. These parameters are obtained experimentally and entered into the memory block. The different values of the coefficients α ₁ and α ₂ are explained by the fact that, when heated, the polyimide film first exhibits temperature shrinkage due to the residual stress arising during the manufacture of the film, and then expands to its inherent coefficient of thermal expansion.

However, the values of the shrink rate and coefficient of thermal expansion are small. The coefficients of linear expansion of the polyimide film α ₁ , α ₂ (unit of measurement K ^-1 ) multiplied by 10 ⁶ are given below.

Temperature ° C In the direction of processing, α ₁ In the transverse direction, α ₂ 23 15,5 37,2 75 16.3 38.9 200 17.8 42.6 300 18.9 45.0

b) Based on the data from the division, multiplication and memory blocks, increments of the size of the plates are determined as the temperature rises: Δа (θ) = α ₁ аθ, Δb (θ) = α ₂ bθ. Because of this, the initial capacitance of the sensor C ₀ increases. The calculation results are summarized in table 1, they are recorded in the memory block.

и выходного напряжения датчика U(θ) от температуры, где Р - пульсации давления.2. Determine the dependence of the capacitance C (θ), the increment of the capacitance ΔC (θ), the conversion coefficient

and the output voltage of the sensor U (θ) versus temperature, where P is the pressure pulsation.

The principle of operation of the sensor. When the pressure changes, the distance between the plates 2 changes. As a result of deformation (a sensor with a solid dielectric) and deflection of the plates (a sensor with a gaseous dielectric), the initial capacitance C, the increment of the capacitance ΔС, and the relative change in the capacitance ΔС / С change. The voltage at the output of the sensor 1 is proportional to the increment of the capacitance ΔС / С and the polarization voltage U _p c of the output of block 4.

.a) The capacitance of a sensor with a solid dielectric is determined by the formula: C (θ) = a (θ) b (θ) ε (θ) / t, increment of the capacitance: ΔС (θ) = С (θ) -С ₀ , where С ₀ - initial sensor capacity at 23 ° C; sensor conversion factor

.

For example, consider a sensor with the dimensions of the plates a × b = 6 × 9 mm; μ = 0.225 - Poisson's ratio; E (23 ° C) = 4.5 GPa - the elastic modulus of the polyimide film; t = 20 microns - film thickness between the capacitor plates; ε (23 ° С) = 3.4 is the initial dielectric constant of the polyimide (at a frequency of 100 kHz). Figure 2 shows the dependence of the dielectric constant of Kapton N (polyimide film) on temperature and frequency. At a temperature of -70 ° C, the dielectric constant varies from 3.3 to 3.45 in the frequency range 0.1-100 kHz. (G. Lee, D. Stoffi, K. Neville. New linear polymers, p.200, fig. VIII.41; M .: Chemistry, 1972, 280 p.)

The temperature dependence of the dynamic elastic modulus of polyimide is shown in Fig. 3 (Bessonov M.I., Koton M.M. et al. Polyimides - a class of thermal polymers, p. 108, Fig. 44; M.-L .: Nauka, 1983 , 306 p.).

The calculated values of the parameters of the sensor with a solid dielectric are presented in the form of a table, displayed on the indicator and entered into the memory unit. In figure 2, 3 and 4, the results are obtained by experimental research.

, где δ - толщина мембраны датчика; коэффициент преобразования:

Когда между обкладками имеется n отверстий, коэффициент преобразования датчика модифицируется:

C₂=ε(θ)(S₀-πa²n)/t - емкость твердотельной части конденсатора (между ячейками), S₀ - площадь обкладки датчика. Все перечисленные параметры датчика с газообразным диэлектриком и зависимость E(θ) от температуры (фиг.3) пересылают в блок памяти, а результаты расчета в виде таблиц подают на индикатор.b) Similarly, the parameters of the sensor with a gaseous dielectric are determined. The sensor capacity, depending on temperature, is determined by the formula C (θ) = πε (θ) and ² (θ) / t = C _g , where a is the cell radius between the plates; capacity increment:

where δ is the thickness of the sensor membrane; conversion factor:

When there are n holes between the plates, the conversion coefficient of the sensor is modified:

C ₂ = ε (θ) (S ₀ -πa ² n) / t is the capacitance of the solid-state part of the capacitor (between cells), S ₀ is the sensor lining area. All of the above parameters of the sensor with a gaseous dielectric and the dependence of E (θ) on temperature (Fig. 3) are sent to the memory unit, and the calculation results are presented in the form of tables on the indicator.

, где U_п - напряжение поляризации датчика. Напряжение U(θ) запоминают и регистрируют на индикаторе.c) Determine the effect of temperature on the output voltage of the sensor:

where U _p is the polarization voltage of the sensor. The voltage U (θ) is stored and recorded on the indicator.

3. The dimensionless coefficients α _{a, b} , α _ε , α _E , α _U are determined as a function of temperature.

a) Take an initial base temperature of 23 ° C. Then, using the functions a (θ), b (θ), ε (θ), E (θ) stored in the memory unit, determine the dependence of α _{a, b} , α _ε , α _E on temperature (Fig. 4). These coefficients are transmitted to the memory unit.

b) In figure 4, the value 1 on the vertical axis corresponds to the initial values at the base temperature of 23 ° C of the coefficients of thermal expansion α _{a, b} , dielectric constant α _ε , elastic modulus α _E , output voltage α _U. From the expression (1-α _{a, b} ) + (1-α _ε ) + (1-α _E ) = 1-α _U according to three coefficients of the sensor itself, the fourth is obtained - the output voltage coefficient: α _U = α _{a, b} + α _ε + α _E -2. The dependence of α _U on temperature is shown in figure 4; it is stored in a memory unit.

Table 1 Parameter Temperature θ, ° С 23 75 200 300 b (θ), mm 9,0032 9,011 9,032 9,051 a (θ), mm 6,0051 6,018 6,051 6,080 C (θ), pF 81.27 81.5 81.98 82.7

0 0.28 0.9 1.73 C (α _ε ), pF 81.27 74 73 72

0 -8.8 -9.8 -eleven

0 -2.5 -7.5 -10

0.2 0.195 0.185 0.18

0.2 0.206 0.213 0.235

0 -eleven -16.4 -20.3 U _o (α _{a, b} , α _ε , α _E ), μV 2 1.87 1.72 1.66 α _U one 0.93 0.86 0.83 Note: in Table 1, a separate indication of the arguments α _ε , α _E , α _{a, b} means taking into account the dependence only on the specified argument; a complete listing of the arguments means that they are all taken into account.

In practice, ΔС / С and U _out (in percent) change identically at 23-300 ° С (0-21%). The change in sizes a and b of the SE from the polyimide film is insignificant (see table 1 and figure 4) in comparison with the variability of ε and E.

4. Graduate the sensor at a known temperature.

a) Without setting (without applying) pressure pulsations, the noise voltage is recorded at the output of the voltage amplifier and fed to the signal input of the memory unit.

b) A known pressure pulsation is applied to the sensor (from an external pulsation generator), the signal of the normalizing amplifier mixed with noise is recorded and stored in the memory unit: the temperature is stored here for calibration. The conversion coefficients of the measuring channels are determined.

5. In the conditions of the experiment (operation), the sensor is subjected to pressure pulsations F at a known temperature. Before the supply of pressure pulsations at a temperature of more than 23 ° C, the voltage of thermal noise is measured at the output of the voltage amplifier.

a) To adjust the effect of temperature on the output voltage of the sensor, the sensor is graduated under normal conditions, i.e. at a base temperature of 23 ° C. The base signal U _o23 from the output of the voltage amplifier is supplied to the signal input of the multiplication unit and multiply U _o23 by a coefficient α _U for a given temperature; receive the expected voltage U _O = U _vyh23 α _U. Next, the signal of the multiplication block is served on the indicator. For example, set the temperature to 80 ° C; at 23 ° C we have a base voltage U _o23 . 4, the output from the multiplier expected voltage U _O = 0,9U _vyh23 carrying information about the pressure pulsation.

и измерительного канала S, на который нужно делить сигнал усилителя напряжения U_вых23, чтобы определить пульсации давления. При температуре эксплуатации сигнал усилителя напряжения U_вых пропорционально пульсации давления подают на сигнальный вход блока деления и делят на коэффициент α_U, чтобы получить U_вых23=U_вых/α_U. Затем с выхода блока деления напряжение U_выз23 поступает на индикатор.b) In the process of calibration at 23 ° C determine the conversion coefficients of the sensor

and a measuring channel S, into which the signal of the voltage amplifier U _output23 needs to be divided, in order to determine the pressure ripple. When the operating temperature signal voltage of the amplifier U _out is proportional to the pressure pulsation is supplied to the signal input divider and divide by the factor α _U, to obtain _vyh23 U _O = U / α _U. Then, from the output of the division unit, the voltage U _call23 goes to the indicator.

6. A pressure pulsation is supplied to the sensor at an unknown temperature.

To ensure measurements, the sensor is graduated at a temperature of 23 ° C and such a value of pressure pulsation P, which is expected in the experiment (operation). The output voltage U _{o23 is} supplied to the memory block.

и измерительного канала S. После запоминания, деления и умножения выходные сигналы блоков памяти, деления и умножения подают на индикатор.Then, during the experiment (operation), it is supplied (applied) to the pressure pulsation sensor P at an unknown temperature. The output voltage of the sensor U _o through the charge and voltage amplifiers and the switch is fed to the signal input of the division unit. At the other signal input of the division unit, the base output voltage U _o23 comes from the memory unit. Dividing unit performs U _O / U _vyh23 and outputs the coefficient α _U and this value is determined by interpolation θ temperature. Moreover, the output voltage for division, multiplication by the coefficient α _U and memorization is fed to the signal inputs of these blocks. To perform the operations of division, multiplication and memorization, the signal of the control unit is supplied to the control inputs of the blocks of division, multiplication, memory and a switch. Then, from the obtained value of the coefficient of output voltage α _U , the value of pressure pulsations is determined and, accordingly, the conversion coefficients of the sensor

and measuring channel S. After storing, dividing and multiplying, the output signals of the memory blocks, dividing and multiplying are fed to the indicator.

Thus, the proposed method of thermal compensation and determination of temperature and pressure pulsations and a device for its implementation compares favorably with the selected prototype and analogue. This is explained by the fact that the dependence of the physicomechanical parameters of the sensor on temperature allows using the well-known electronics units (memory, division, multiplication and switch) to determine the pressure and temperature of the object. Provides high accuracy without loss of time during operation. Due to this, the technical and economic effect of measurements is increased.

TsAGI conducted metrological experiments in the temperature range 23-300 ° C. They confirm that with an increase in temperature, errors increase due to a decrease in the elastic modulus and dielectric constant of the film. From the results of table 1 and figure 4, it is concluded that to compensate for the error, it is advisable to calibrate the sensors in conditions close to operational (temperature). At the same time, a temperature of 60 ° C is set on the sensor, pressure pulsations from 55 dB to 120 dB with a frequency of 40, 100, 1000 Hz, in this experiment, the output voltage coefficient is not more than α _U ≈ 0.98, i.e. the effect of temperature on pressure pulsations is not more than 2%.

The stability of thin-film sensors with solid (DET-3) and gaseous (DEG-4) dielectrics was also experimentally studied in the temperature range 23-60 ° C at a pressure pulsation with a frequency of 40 Hz. The thickness of the polyimide membrane is 20 μm, the elastic modulus E = 4.5 GPa, the dielectric constant ε = 3.4 at a temperature of 23 ° C. After subtracting the errors of the pulsation generator and measuring instruments, a residual error of not more than 3% is obtained.

Claims (2)

1. A method for determining pressure pulsations, based on the fact that a pressure is applied to a capacitive sensor, which is converted into an electrical signal, amplified and recorded, then, at rest under normal conditions, the sensor is graduated and noise voltages are determined, then the sensor is placed in an elevated temperature environment , the voltage of thermal noise is measured at its output, the temperature of the medium is determined, the pressure pulsations are determined, characterized in that the pace is determined before determining the pressure pulsations at rest of the sensor -temperature dependence of the permittivity ε, the modulus of elasticity E and sizes electrodes a × b of the sensor is then determined metrological characteristics capacitive sensor (with a solid or gaseous dielectric), namely capacitor C, an increment ΔS container transform coefficient

where P is the pressure pulsation and the output voltage U _o , then the temperature dependences of the coefficients for the dielectric constant α _ε , the elastic modulus α _E and the thermal expansion of the plates α _{a, b} , and the output voltage α _U are calculated, taking the base temperature equal to 23 ° C, all the above dependencies are remembered, from the sum of (1-α _{a, b} ) + (1-α _ε ) + (1-α _E ) = 1-α _U , the output voltage coefficient α _U = α _ε + α _E + α is obtained _{a, b -2,} all parameters of the sensor are in the form of tables and recorded, then the sensor is placed in an environment with known tamper uroy above 23 ° C, is fed, controlled pressure P ≠ 0, the known temperature value determined coefficient α _U output voltage is then measured output voltage U _O, carrying information about a change in pressure, this voltage is divided by the coefficient α _U output voltage obtained base value output voltage U _o23 and sensor conversion coefficient

; if operating conditions of the sensor temperature is unknown, then the sensor is fed controlled pressure, calibrated at 23 ° C, is measured and stored basic output voltage U _vyh23, then the sensor is supplied at the same pressure at elevated temperature, measured output voltage U _O and divide it to the base output voltage U _o23 , receiving the value of the coefficient α _U , the operating temperature is calculated from it, and the operations of memorization, division and multiplication are carried out according to the control signals. 2. A device for determining pressure pulsations, comprising a capacitive sensor, a charge amplifier, a voltage amplifier and a polarization unit, in which the output of the polarization unit is connected to the capacitor plate, and the other capacitor plate is connected to the input of the charge amplifier, the output of which is connected to the input of the voltage amplifier, characterized the fact that the device has memory, division, multiplication, control and switch blocks that are connected to the signal output of the voltage amplifier, the switch output is connected to the inputs of the unit s division, multiplication, and memory storage unit coupled to the switch and outputs the division and multiplication unit, an output of division blocks, multiplication, and a memory coupled to the indicator and control unit connected to control inputs of memory blocks, multiplication, division, and a switch.

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