SU1657987A1 - Method of measurement of pressure and device for its implementation - Google Patents

Abstract

The invention relates to measuring technology. The aim of the invention is to improve the accuracy of the device for measuring pressure by eliminating temperature errors and expanding its functionality (simultaneous measurement of pressure and temperature). The invention consists in measuring the electrical resistances of two strain gauges of different sensitivity 2 while simultaneously influencing the pressure and temperature of the medium being measured and calculating the measured values of the resistance values of pressure and temperature using formulas, n type third polynomials of the resistances of the first and second sensitive elements , obtained by graduation and computer processing. Sensitive elements are made of monocrystals of samarium sulfide doped with selenium, and their degree of doping is different. 2 sp.fl, 1 silt with SS (L S

Description

The invention relates to a measurement technique, namely, to means for measuring pressure.

The aim of the invention is to improve the accuracy of pressure measurement by eliminating the temperature component of the error and expanding the functionality of the measuring device by simultaneously measuring pressure and temperature.

The drawing shows a block diagram of the device. The sensing element of sensor 1 is made of two crystals of samarium monosulfide 2 with different sensitivity, which are placed on a dielectric sleeve 3, pressed into the housing 4, the internal cavity of which is connected to the measured medium by the holes 5. Conclusions 6 of the sensitive element pass through the insulating tube 7 to the sensor head 8, in which the dielectric block 9 is placed with screws 10 for fastening the leads of the sensitive element and connecting the connecting wires connecting the output of the sensor 1 through switch 11 to the input of the measuring bridge circuit 12, the output of which via an analog-digital converter 13 po0 CO

-h

CO 00

-vj

steps into the memory of the computing device 14, and the result of the calculation of physical quantities and pressure and temperature is displayed on the display unit 15. The power of the measuring circuit is provided by the power supply 16, and the control block 17 controls the operation of the measuring device as a whole.

The method is carried out as follows.

The measurement is performed in two cycles.

In the first measurement cycle, the switch 11, being in the first position, connects the output of one of the crystals to the input of the measuring measuring circuit 12, and the result of measuring its resistance is converted into a binary-decimal code using an analog-digital converter, 13 and entered into memory computing device 14.

I On the second measurement also, the switch 11, at the command of the control unit 17, connects the output of a second crystal to the input of the measuring circuit 12, the resistance of which is similarly converted into a code and also stored in the memory of the personal device 14.

I

Then at the command of the control unit

17, the computing device 14 converts the codes of the output signals of the sensor into decimal codes corresponding to the values and dimensions of the physical values of pressure P and temperature T according to the following formulas

Р A0 A, R4 + AtR2 + AEC + + A4R, R2 + A5R + A6R + A7R (R4 +

+ AgR, Ri, (1)

T B0 4- B, R, - B2RZ + BjRf + +, + B5Rj + B6Rf + ((2) 50

where R, Rj, - codes of electrical resistance of crystals. The coefficients A0, A, A, A, A, Ay, Aw, A7, Ab and Bb B, Bg, B ,, 55

B4, B, B6, B by the formulas (1), (2) are obtained by calibration and are permanently stored in the memory of the WU.

0

0

The switch 1 1, remaining in the second position, ensures that the measuring device is ready for the next measurement cycle of the resistances of the sensing element of the sensor, but now in reverse sequence - K.- ,, K.

Formulas (1) (2) are obtained as follows.

The calibration characteristics of two samari monosulfide crystals of different sensitivity R f (P, T), Rt f (P, T) were experimentally obtained. Then, using a computer using the least squares approximation program with a static analysis of the accuracy of the approximation, the numerical values of the coefficients in formulas (1) and (2) were obtained.

Claims (2)

1. A method of measuring pressure, including loading a crystal of samarium monosulfide doped with selenium, measured by pressure, measuring its electrical resistance, converting electrical resistance to a numerical code, and calculating the measured pressure using the inverse transformation formula, characterized in that, in order to improve the measurement accuracy pressure by eliminating the temperature component of the error and extending the functionality by simultaneously determining the temperature load pressure measured emym second crystal monosul- feed samarium, l and m of h and Yusch and with a first degree of doping the crystal selenium, its resistance is measured, which is converted into a digital code, and the values of pressure P and temperature T is determined by the formulas 2 P - A0 A, R, + + AjR, + + A4R, R2 + A5R + A6R + + + AgR1R2, T - B0 + B4R, Rj, + BSR | + BgR + BrRfll2) T - B0 +, + BZR2 + B3R, + where Rj and R are the resistances of the first and second crystals; L8 0, L ,, Ar, and BO, B, R rt g five A4, A sixteen AT 5 H6 7 3 B Bf B7 - numerical coefficients, which are predefined with using graduations 2. A device for measuring pressure, comprising a housing in which a first crystalline sensitive element, made of samarium monosulfide doped with selenium, and a pavement measuring circuit, the output of which is connected via an analog-to-digital converter, is installed, equipped with an indicator, characterized in add to it 1657987 A two-channel analog switch, control unit and the second sensitive element mounted in the housing and made of samarium monosulfide doped with selenium with a lower degree of doping with selenium than the first sensitive element connected to Q to the first input of the analog switch, and the second to its second input, the switch output connected to the input of the bridge measuring circuit, and the output of the control unit connected to , 5 control inputs of the switch, analog-digital converter and computing device. eight