SU1597540A1 - Device for measuring linear displacements - Google Patents

Abstract

The invention relates to a measurement technique and can be used to measure linear displacements. The aim of the invention is to improve the measurement accuracy by compensating for temperature errors. When the temperature changes, the speed of wave propagation in the fixed plate 3 changes. This change is compensated by the bending of the bimetallic frame 10 and, therefore, the plate 3. 1 Il.

Description

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The invention relates to a measurement technique and can be used to measure linear displacements.

The aim of the invention is to improve the measurement accuracy by eliminating temperature errors.

The drawing shows a schematic of the device dp measuring linear displacements.

The device comprises a generator 1, the output of which is connected to the direct-pin converter 2 of the fixed piezoelectric plate 3 and the first input of the phase meter 4, the output of which is connected to the reading unit 5. The second input of the phase meter 4 is connected to an interdigitated transducer 6 of a movable piezoelectric plate 7. A stationary piezoelectric plate 3 with surface absorbers 8 mounted at the ends of the absorbers 8 is rigidly attached to the carrier plate 9 (for example, glue), which has one end rigidly connected (for example, welded) with a bimetallic frame 10, and the other end connected to it with an adjustment screw 11,

 . The device works as follows.

When applying the excitation voltage from the generator 1 (e.g., quartz), the interdigital transducer 2 excites an acoustic wave propagating to both sides of the stationary piezoelectric plate 3. One wave (left) at the end is absorbed by the absorber 8 surface acoustic waves, the second ( the right reaches the movable plate 7 and is received by the interdigital transducer 6, after which it is fed to the phase meter 4. The signal from generator 1 is sent to the other input of phase meter 4, you move the phase meter to block 5 to read audio. The measured phase angle is directly proportional to the distance from the fixed rolling 2 to 6 meetings but interdigital transducer. Referring extends further to the right, the wave is absorbed at the end of the piezoelectric plate 3 absorber 8.

A change in temperature leads to a change in the speed of propagation of the surface acoustic wave and a change in the length of the plate 3. Since the phase is

txj 1.

21G

L

v

-.P,

where f is the frequency;

L is the distance from the interdigital transducer 2 to the interdigital transducer 6; wave speed; integer, this causes a change in cf and a measurement error of the displacement dX, which is determined by the magnitude of L. Relative error

V

P

a (

-uLj

4Y

0

five

0

where L- and iV are increments from temperature.

At the same time, a change in temperature leads to the bending of the bimetallic frame 10, which, through the adjusting screw 11, which serves for the initial tension, bends the non-dried plate 9 and, together with it, the fixed piezoelectric plate 3. The bending of the bimorphic 10 and piezoplates 3 causes a phase change

y.

four

L

V

where uljg deformation in direction

wave propagation. The bimetallic pair: frame 10 and the dry plate 9 are selected so that the phase change of the fixed plate 3 due to the temperature change and the phase change dCfj due to the deformation of the piezoplate 3 bi-. metal frame 10 satisfy the condition

/ iqi - L qjg,

in this case, the temperature error is compensated, which leads to an increase in the measurement accuracy. .

Formula of the invention A device for measuring linear displacements, comprising a generator, fixed and movable piezoelectric plates with interdirectional transducers, surface acoustic wave absorbers and a phase meter connected in series, to the first input of which is connected

A movable transducer is mounted on a carrier plate of an electroelectric plate, and the blockyntine, surface-absorbing absorbers, distinguished by physical waves, are located at the ends

the fact that, in order to ensure accuracy of the motionless piezoelectric plasma measurement, it is equipped with a bimetaplication, and the carrier plate is fixed

which frame bearing ppastina and yusti-on the bimetallic frame with one end

rotor screw, the generator is connected tightly, and the other is connected with the help of the second input of the phase meter and from the reversing screw with the possibility of a non-pinable transducer not suitable for bimetallic

Viznogo piezoelectric plate, frame.

Claims (1)

Claim A device for measuring linear displacements containing a generator, fixed and movable piezoelectric plates with interdigital transducers, absorbers of surface acoustic waves and a phasometer connected in series, to the first input of which there are connected 5 1597540 no-pin transducer of a movable piezoelectric plate, and a reading unit, I distinguish Furthermore, in order to increase the measurement accuracy, it is equipped with a bimetallic frame, a bearing plate and an adjustment screw, a generator with the second input of the phase meter and with the interdigital transducer of the fixed piezoelectric plate, which is mounted on the carrier plate, the absorbers of surface acoustic waves are located at the ends of the stationary piezoelectric plate, and the carrier plate is fixed on the bimetallic frame with one end rigidly and the other with the help of an adjustment screw with the ability to move relative to the bimetallic frame.