SU504940A1 - Piezoelectric vibroaccelerometer - Google Patents

Description

one

The invention relates to the field of measurement technology.

The known piezoelectric vibroaccelerometers, containing a sensitive piezoelectric element, mounted between the base and the inertial mass and connected via cables to the indicator, do not in all cases provide simultaneous measurement of vibration accelerations along three axes of coordinates and have low accuracy and sensitivity of measurements.

To ensure simultaneous measurement of vibration accelerations along three coordinate axes with an increase in accuracy and sensitivity in the proposed vibroaccelerometer, the sensitive element is made in the form of a rectangular parallelepiped of crystal, the piezoelectric constant matrix of which has the following form:

OOODi5 About

OOOd24 GS

dsi d32 dsa ltd

moreover, the polar axis of the crystal is perpendicular to the plane of attachment.

FIG. 1 shows a general view of a vibroaccelerometer (the X, Y, Z symbols indicate the axes and faces of the piezoelectric element; two parallel faces and perpendicular to them are the axes marked

the same symbol); in fig. 2 - block circuit of its inclusion.

The vibroaccelerometer contains a piezoelectric element 1 located between the base 2 and the inertial mass 3 and representing a rectangular parallelepiped with metallized faces, which are connected in pairs through pins 4, 5, 6 (Fig. 2) and preamplifiers 7, 8, 9 to the load ones cables m 10, I, 12 and further to indicators 13, 14 and 15.

The piezoelectric element 1 is made of a crystal, the matrix of the piezoelectric constants of which has the form

0OOOdi5 About

OOOd24 GS

dsi d32 dss ltd

At the same time, some of the non-zero zero piezoelectric constants of this matrix dai, d2, das, d24, dis can be equal to each other.

The class of materials with the above piezoelectric constant matrix is wide enough and to select a material with increased sensitivity (the sensitivity of the vibroaccelerometer is determined by the ratio of the piezoelectric constant d to the dielectric constant e of the material) you can use the following table:

The polar axis of the piezoelectric element 1 is perpendicular to the plane of attachment. Preamplifiers 7, 8, and 9 (either in voltage or in charge) are made on the basis of a field effect transistor and are located on or near the body of the vibroaccelerometer.

When measuring the vibration along the Z axis, a strain-strain in the same direction occurs in the crystal, the piezoelectric constant d is triggered and charges appear only on the faces of Z. In the case of vibration in the direction of the X-axis, shear strain occurs in the plane XZ, the piezoelectric constant dis is triggered, and charges occur only on face x X. With vibration in the direction of the Y axis, shear deformation occurs in the YZ plane, the piezoelectric constant 24 is triggered, and charges appear only pas gran x Y.

Since no X-strain deformation is created in the directions of the X or Y axes, the piezoelectric dsi and dz2 of the crystal are not involved in the operation of the vibroaccelerometer. If the vibration is directed arbitrarily in space, then using three piezomodules (, cfis, 24), operating simultaneously, three projections of this vibration on the X, Y and Z axes can be obtained.

Thus, the use of three piezoelectric constants / 3, di5 in a crystal allows one to accurately determine the vibration acceleration vector at a given point in space with a minimum of parasitic sensitivity.

Claims (1)

Invention Formula A piezoelectric vibroaccelerometer containing a sensitive piezoelectric element mounted between the base and the inertial mass and connected via cables to an indicator, characterized in that, in order to ensure simultaneous measurement of vibration accelerations along three axes of coordinates with an increase in accuracy and sensitivity of measurements, the sensitive element is designed as a rectangular parallelepiped of crystal, the matrix of the piezoelectric constants of which has the following form: OOODi5 About OOOd24 GS dsi d32 dsa ltd moreover, the polar axis of the crystal is perpendicular to the plane of attachment.