SU1379656A1 - Pressure pickup - Google Patents

Abstract

The invention relates to measuring technique and allows to increase the sensitivity of the sensor. On the base 5 in the housing there is a rectangular membrane 1, on the surface of which an active 2 is placed in the center of it, and a compensatory 3 resonators on the thickened edge. These resonators are made in the form of an array of interdigital transducers of surface acoustic waves with strip reflectors. The pressure affecting the sensor is characterized by the difference in the frequencies of the resonators 2 and 3. A change in the ambient temperature leads to a shift of the initial frequencies of the resonators 2 and 3 by the same time. The mask does not affect the output characteristic of the sensor. The thickness of the membrane 1 is selected for at least six lattice periods of counter-whip transducers, and its width exceeds the aperture of these transducers by at least two times. 1 3.p. f-ly, 3 ill. S (l

Description

OO

vj

with

O5

ate

ot

OL / GE

The invention relates to instrumentation engineering and can be used to measure the pressure of gaseous or liquid media.

The purpose of the invention is to increase the sensitivity,

FIG. 1 shows a sensor, a longitudinal section J in FIG. 2 - the same cross section; in fig. 3 - topological structure of surface-acoustic resonators, top view

The pressure sensor comprises a rectangular membrane 1 with thickened edges made of quartz, for example a Y-cut. On the membrane surface in its center is placed an active resonator 2, which is oriented along the axis parallel to the larger side of the membrane. A compensating resonator 3 is placed on the flat edge of the membrane 1. Resonators 2 and 3 are made in the form of an array of interdigital transducers of surface acoustic waves with strip reflectors. With the help of an elastic compound 4, the membrane is fixed on a metal base 5, in the center of which a hole is made with a branch pipe of 6 lp p. –lchchi pressure. To protect the environment from the outside environment, the housing 7 is used. Using germs 8 and 9 of the controllers 2 and 3, you connect Ue.pe: trillion scheme.

The pressure sensor works as follows,

The pressure measured on the membrane i causes longitudinal and transverse deformations of the surface layer, H; the volume of the resonator 2 decreases in proportion to the measured pressure measured, and the frequency of the resonator 3 under the influence of pressure does not change, since the thickened edge of the Hbi 1 membrane is placed. The change in the ambient temperature hinders the displacement of the initial frequencies of the resonators 2 and 3 by the same u shape. In this case, the frequency difference between the resonators 2 and 3 depends only on the magnitude of the pressure. The thickness is chosen to be greater than the six lattice periods of the interdigital probes due to the fact that the faithful acoustical waves are localized in a layer of not more than three wavelengths in depth (three intermittent periods of transient; pin-pin converters) and the membrane bend has

0

a neutral surface that does not experience bending deformations, i.e. The membrane thickness must be at least six lattice spacing of the interdigital transducers. The aperture of the interdigital transducers of the active resonator 2 does not exceed half the width of the membrane,

Q because, with a rigid clamping of the membrane, its central region experiences tensile deformations. The dimensions of the region of positive deformations of the rectangular membrane 1 are not less than half of its width,

therefore, the width of the membrane should not less than twice the aperture of the interdigital transducers. The choice of temperature

0 coefficient-, oi linear expansion of the base of the condition

Dt, "". "Oi ,,

where d and 2 are the temperature coefficient of linear expansion of the membrane in the longitudinal and transverse directions,

allows y (-1) the temperature component of the sensor error.

Compared to the IRG sensors, the dp sensor is characterized by an increased (by a factor of 3-10) sensitivity. five

Claims (2)

1. A pressure sensor containing 0 rectangular membrane Е (with thickened peripheral part, installed;.;; on the base in the housing, the active resonator of surface acoustic waves, placed on the membrane along 5 of its central longitudinal axis., H is a compensated resonator on top of an I: OCT acoustically ;; ryuls, Razyg-Olennvd on the thickened peripheral part of the membrane, (features contain resonators Q counter-pin transducers 1; optics; e1 acoustic waves in the nmde res. 1-i, distinguishable and T-M, (TO, in order to increase the sensitivity, it has at least one of the grating periods no-pin transducers, and the membrane irin exceeds the aperture of meetings of o-pin transducers by at least two times. 2. The sensor according to claim 1, characterized in that the temperature coefficient of the linear expansion of the base (/ d is selected from the condition, oi oij th 13796564 where ot, and oL 2 are the temperature coefficients of linear expansion of the membrane in the longitudinal and transverse directions. QJUZl