SU1339423A1 - Pressure transducer - Google Patents

Abstract

This invention relates to a measurement technique. The purpose of the invention is to improve the measurement accuracy. The measured pressure is sensed by the membrane 1, it bends along with the piezoelectric plate 4 inside the housing 2. The thickness of the air gap between the piezoelectric plates 4 and 7 decreases. Since the latter are included in the autogenerator circuit made on the amplifier 9, the excitation of which occurs at the resonant frequency of the air gap, the frequency of the oscillator smoothly changes in proportion to the displacement of the membrane 1. 2 Il. $ (L 7/2 U / / X lyvv; J Swxo

Description

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The invention relates to a measurement technique and is intended to measure and control pressures.

. The aim of the invention is to improve the measurement accuracy.

Figure 1 shows the block diagram of the sensor; Fig. 2 shows a pressure sensor, a cross section.

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The pressure sensor consists of Q-membrane membranes acting on sinusoidal voltages, the frequencies of which are determined by the resonant properties of the air gap between two adjacent piezoelectric plates.

From the output of the autogenerator amplifier 9, the signal is a function of the temperature and the measured pressure P, and from the output of the autogenerator amplifier 10 it is only a function of the air temperature inside the sensor housing. These signals are fed to the inputs of a two-frequency difference meter, the output of which is proportional to the measured pressure P. Damping pads 3, 5 and 8 are necessary to prevent generation of the pressure sensor at the resonant frequency of the mechanical system. Due to the frequency output, the sensor is easily matched to the secondary signal processing equipment.

us 1, zakryashayuschey body 2 of the sensor, to which through the damping gasket-. A piezoelectric plate 4 is attached to the base 3. A piezoelectric plate 6 is fixed to the base of the body through a damping gasket. At equal distances from the piezoelectric plates 4 and 6, a piezoelectric plate 7 is attached to the body walls through the damping gaskets 8. The plates are hingedly included in the circuits two oscillators made on amplifiers 9 and 10, the outputs of which are connected to the inputs of the meter 11 of the frequency difference.

The sensor works as follows.

The measured pressure P is perceived by the membrane 1, it bends together with the piezoelectric plate 4 inside the housing 2. At the same time, within the limits of the elastic deformation of the membrane, the thickness of the air gap between the piezoelectric elements 4 and 7 is reduced. Since these piezoelectric elements are included in the oscillator circuit, performed on amplifier 9, which is excited at the resonant frequency of the air gap, the frequency of the oscillator smoothly changes in proportion to the movement of the membrane 1.

Piezoelectric plate 6 is used for temperature compensation of the sensor. Together with the piezoelectric plate 7, it is included in the circuit of the second oscillator performed on the amplifier 10. This oscillator is excited at the resonant frequency of the air gap between adjacent piezoelectric elements 6 and 7. Since these piezoelectric plates are stationary, the frequency of the second oscillator is a function of the physical state of the air gap between them. The main parameter of the state of air, affecting the frequency

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Claims (1)

Invention Formula A pressure sensor containing a hollow cylindrical body, on the open end of which a membrane is installed, two piezoelectric elements located in the internal cavity of the body, one of which is fixed on the membrane and the other at the bottom of the body, and an autogenerator in which the piezoelectric elements are different. the fact that, in order to increase accuracy, it is equipped with a third piezoelectric element, located at an equal distance between the first and second piezoelements, an additional autogenerator and a frequency difference meter, while all the piezoelectric elements s are identical in form of plates and are mounted on coplanar pads, oscillators inputs are connected to the electrodes of the third piezoelectric element, and outputs - to the electrodes of the first and second pezoelemen- comrade, respectively, and to inputs of the frequency difference meter. is temperate339423 that generator, tour. Amplifiers 9 and 10 can be equipped with automatic gain control, which eliminates the active elements of the amplifiers. Thus, in the positive feedback circuit, autohero 0 five 0 five Invention Formula A pressure sensor containing a hollow cylindrical body, on the open end of which a membrane is installed, two piezoelectric elements located in the internal cavity of the body, one of which is fixed on the membrane and the other at the bottom of the body, and an autogenerator in which the piezoelectric elements are different. the fact that, in order to increase accuracy, it is equipped with a third piezoelectric element, located at an equal distance between the first and second piezoelements, an additional autogenerator and a frequency difference meter, while all the piezoelectric elements s are identical in form of plates and are mounted on coplanar pads, oscillators inputs are connected to the electrodes of the third piezoelectric element, and outputs - to the electrodes of the first and second pezoelemen- comrade, respectively, and to inputs of the frequency difference meter. Compiled by M. Zhukov Editor I. Shulla Tehred V. Kadar Proofreader E. Roshko 4212/32 Circulation 776 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 ig.2