SU1507015A1 - Device for measuring pressure - Google Patents

Description

(46) 04.30.91. Null No. 16 (21) 4157581/10 (22) 12/08/86

(71) Special design bureau of magnetohydrodynamics of the Institute of Physics of the Academy of Sciences of the Latvian SSR and the State Research Institute of Heat and Power Instrumentation

(72) I.P. Kwasniewski, M.N. Levin, A.M. Lipschsch, S.P. Prokoshev, V.A. Puginsky and V.I. Yakushonok

(53) 531.787 (088.8)

(56) Levshina B.C., Novitsky P.V. Electrical measurements of physical quantities. L., 1983, p. 186-190.

USSR author's certificate 998881, cl. G 01 L 9/10, 19.81. (54) DEVICE FOR MEASURING PRESSURE

(57) The invention relates to instrument making and permits an increase in the accuracy of pressure measurements due to

decrease in temperature fluxes; For this, along with the elastic sensing element 1 in the housing 3, the magnetic CHCTCMoii 7 with the AC excitation winding 9 and the indicator device 32, the device contains differential amplifiers 21 and 24, a voltage relation unit 30, a movable 5 and a fixed 6 plate with a conductor 1 and frame 14, respectively, installed in the gap of the magnetic system 7, the conductor 11 is connected to the midpoint 15 of the one-turn frame 14 by means of a flexible jumper 18. When pressure is applied to the elastic element I, the conductor I1 is shifted relative It is possible to rework 14, which changes the voltages at the ends 16 and 17 of frame 14. The ratio of the difference between these voltages and their sum is an output signal, linearly dependent on pressure. 2 Il.

w with:

The invention relates to instrument engineering and can be used to measure the pressure of media under conditions of temperature effects.

The aim of the invention is to improve the measurement accuracy by reducing temperature errors, inertia and nonlinearity.

FIG. I schematically depicts the proposed device, the cut; in fig. 2 - the same electrical circuit.

The device contains an elastic sensitive element I with a rod 2,

which are placed in the housing 3, the stem 2 passing through the hole in the upper flap 4 of the housing 3. The first plate 5 is fixed on the stem 2, and the second plate 6 is fixed on the stem 2 of the housing 3 parallel to the first plate. Electromagnet 7 is mounted using fastening elements 8 on the top cover 4 of the housing 3 in such a manner that both plates 5 and 6 are in its gap and parallel to the working surfaces of its poles. The winding 9 of the electromagnet 7 is connected to the power source of the variance of h

about ate

10 current, on the first plate 5 is fixed nirvink 11 with conclusions

12 and 13; On the second plate 6, a single-turn rectangular frame of conductor A is attached, with the midpoint terminal 55 and terminals 16 and 17. The second plate 6 is mounted

on the top krppke 4 housing 3 such

in such a way that the middle line of the rectangular frame (in FIG. 2 is shown by dotted lines). parallel to the conductor 1I of the first plate 5, the terminal 12 of the conductor I1 of the first plate 5 and the output of the midpoint 15 of the rectangular frame 14 of the second plate 6 are connected by a flexible electrically conductive jumper 18 (shown in Fig. 2 schematically). Conclusion

13 conductor P of the first plate 5 is grounded. The projection of the conductor 1 I to the rectangular frame in the direction of the magnetic field lines divides the area of the frame 14 into two equal parts. The terminals 16 and 17 of the frame 14 of the second plate 6 are connected to different (plus and minus) inputs 19 and 20 of the first differential amplifier

21, as well as with one-digit (for example, plus) inputs 22 and 23 of the second differential amplifier 24, the input 23 of another sign (minus) of which is grounded. The outputs 26 and 27, respectively, of the first 21 and second 24 differential amplifiers are connected to inputs 28 and 29, respectively

voltage ratio block 30, Output 31 of voltage ratio block 30 is connected to the indicator device 32.

The pressure measurement device operates as follows. In the gap of the electromagnet 7 acts a uniform alternating magnetic field. In the absence of a measured pressure on the conductors 16 and 17 of the frame 14 relative to the end 13 of the conductor I1, antiphase voltages of the same amplitude are induced, therefore, at the output 31 of the voltage ratio unit, the output signal will be zero,

When a measured pressure is applied to the sensing element 1, the rod 2 is shifted by an amount proportional to the pressure. In this case, plate 5 with conductor I1 will shift relative to the center line of the rectangular

the frames 14 on the plate 6 and on the terminals 16 and 17 of the voltage frame 14 will have different amplitudes, which will be given by the corresponding signal at the output 27 of the amplifier 24 and at the output 31 of the voltage ratio block 30, which will be fixed by the indicator 32,

The use of the invention will eliminate the main sources of both additive and multiplicative temperature errors, while ensuring linearity of the characteristics and reducing inertia.

Claims (1)

Invention Formula A device for measuring pressure containing an elastic sensing element in a housing, a magnetic system with an alternating current winding, and an indicator device, characterized in that, in order to improve measurement accuracy by reducing temperature errors, inertia and nonlinearity, it is equipped with two differential amplifiers, the ratio unit tension and two plates, mobile and fixed, on which the conductor and single turn frame are fixed, respectively, with the output of the middle point and flexible electrical The bridge is bridged, and the magnetic system is made in the form of an electromagnet with a plane-parallel gap between the poles 1, in which the plates are placed, the movable plate being rigidly connected to the elastic sensor element, and stationary fixed to the housing; a jumper with a midpoint output of a single-turn frame of a stationary plate, and the other is grounded; the conclusions of a single-turn frame of a fixed plate are connected to different inputs and inputs of the first a differential amplifier with single-input inputs of a second amplifier, the input of a different sign of which is grounded, the outputs of both differential amplifiers are connected to the inputs of the unit with relative voltages, the output of which is connected to the indicator device.