SU1434567A1 - Unit for calibrating acoustic pressure transducers - Google Patents

Abstract

The invention relates to an acoustic measuring technique. The aim of the invention is to reduce the calibration error due to the compensation of external seismic effects. The installation contains an additional identical measuring chamber with a piston, installed parallel to the main chamber, and a balanced lever, the ends of which are attached through backlash-free hinges to the piston rods of the measuring chambers, and the drive is complete in the form of two electric machines mounted on one axis. 1 З..П. f-ly, 1

Description

22

U

with

four

cl

Od

23

The invention relates to acoustic measurement technology and can be used for the calibration of acoustic transducers.

The purpose of the invention is to reduce the calibration error due to the compensation of external seismic effects.

The drawing shows the proposed installation.

The installation for calibration of acoustic pressure transducers consists of a given generator 1, amplifier 2 power S, stabilized sources 3 and 4 of direct current, a drive in the form of electric, synchronous machines 5 and 6. The electric synchronous machine 5 produces a return electrical function springs and consists of rotor 7 and stator 8 connected to power supply 4, Electric Mapina 6 performs the functions of a harmonic oscillator and consists of a rotor 9 connected through a power amplifier 2 to a generator Atator 1 and stator 10 J connected to power supply 3, the shafts of both machines are rigidly connected with the help of coupling 11. On the output shaft of the harmonic generator 6, a reading device in the form of inductosin with a rotor winding 12 and a stator winding 13 is attached to the recording device 14 ,, a lever 15 connected to a piston rod 16 and 17 by means of helpless and backlash-free hinges 18 and 19. UITOKH pistons with pistons 20 and 21 are located in two push-mounted installed ideally measuring chambers 22 and 23,

The device works in the following way.

From the stabilized source 4, the voltage is applied to the rotor winding 7 and the stator winding 8 of the return electric spring 5, from the power source 3 the voltage is applied to the stator winding 10 of the harmonic oscillator 6. When alternating voltage is supplied from the master oscillator 1, the rotor 9, the inductosin rotor 12, the balanced lever 15, which, in turn, moves the linear rods through the backlash joints 18 and 19, through the amplifier 2 to the rotor winding of the harmonic oscillator. 16 and 17 tailors

g

. 0 5 Q,.

,

five

0

and pistons 20 and 21 in chambers 22, 23. The role of the return electric spring is that, in the absence of a signal, it returns the rotor 9 to a state of static equilibrium.

When the rotor 12 of the inductosyn rotates relative to the stator 13 through the angle 0, an electrical signal is applied to the registering device 14, which is proportional to the movement of the pistons in the chambers and the values of reproducible pressures.

With relatively small displacements

x piston rods and with respect -

R

0.01, the value of H is determined from the formula for the central angle of the circle H, where H is the swinging pitch of the scientific research institute of piston rods; o (is the angle of rotation of the induktoshina rotor relative to the stator, R is the radius of rotation (lever shoulder).

The reproduction pressure in the measuring chambers is determined from the formula

P KrK Po-N-S -2H 2V,

where Vg is the volume of the chambers;

P - amplitude of reproducible

pressure;

PQ - static pressure in the measuring chamber; K - coefficient taking into account

the distribution of sound pressure in the chambers -, K - coefficient, the learning volume introduced into the chamber -; S (, is the piston area;

N is the coefficient of polytropes; 2H - swing piston. In the installation, harmonic oscillations of the generator are performed around the horizontal axis due to the use of two synchronous machines and a balanced lever as a drive, as a result of which seismic and other external loads are perceived by the bearings of the machine supports, creating a moment of resistance to oscillations whereby the calibration error is reduced.

Claims (2)

1. Installation for the calibration of acoustic transducers. containing a master oscillator connected to a power amplifier, a measuring chamber with a piston, combining HeHittiM with a drive, and a reading device for moving the piston, characterized in that, in order to reduce the error due to the compensation of external seismic influences, it is equipped with an additional identical measuring chamber with a piston installed in parallel with the main chamber, and a balanced lever, the ends of which are fixed through the backlash-free hinges to the piston rods of the measuring chambers, while the output shaft is driven firmly fixed -len in the center of a balanced lever symmetrically relative to the axes of the piston rods, and the drive is made in the form of two synchronous electric machines fixed on the same axis to the output shaft, the stators and the rotor of one of which are connected to a DC source and the output of the other machine power. 2. Installation according to claim 1, characterized in that the reading device for moving the piston is made in the form of an inductosin, the rotor of which is attached to the output shaft of the drive, and the stator is connected to a recording device.