RU1776451C - Electroacoustic converter - Google Patents

Abstract

The invention relates to acoustic technology, in particular to devices for generating powerful periodic sound vibrations. The electro-acoustic transducer comprises a series-connected discharge chamber with two electrodes, an inductor, a capacitor charged from an external current source, and a pulse transformer, the primary winding of which is connected to the ignition pulse source. The introduction of an inductor and the placement of a discharge chamber with electrodes in the magnetic field of this coil is new in the converter. 1 ill.

Description

The invention relates to acoustic technology, in particular to devices for generating powerful sound vibrations, and can be used in systems for acoustic and radio-acoustic research of the atmosphere, for vibration testing of structures in a gas environment, for acoustic studies of limited volumes filled with a gas medium (pipelines, wells, mines, etc.).

Known electro-acoustic transducer (AS USSR No. 485782, class B 06 V 1/02, 09/30/75), using an arc discharge and containing a discharge chamber formed by the poles of an electromagnet, in the form of a longitudinal gap in which two main and one auxiliary (igniting) electrodes and a horn matching the acoustic transducer with the environment. Sound pulses or periodic oscillations in the form of a sequence of pulses are obtained as a result of single or periodic ignition and quenching of the arc discharge. The electric arc between the main electrodes is ignited with the help of an auxiliary electrode; therefore, a voltage sufficient to develop an independent discharge must be applied between the main electrodes, i.e. several kilovolts. The quenching of the arc occurs as a result of its breaking at the ends of the electrodes when moving in a magnetic field.

A disadvantage of the known electro-acoustic transducer is its low efficiency, due to significant energy losses in the power supply circuits, low arc resistance and the need for an additional power supply for the electromagnet.

The closest technical solution, selected as a prototype, is an electro-acoustic transducer (AS USSR No. 869839, class B 1/02, 10/07/81) containing a discharge chamber with two electrodes, a capacitor charged from an external current source, and a pulse transformer, the primary winding of which is connected to the source of ignition pulses. In a known converter

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with

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arc burning stops after the discharge of the capacitor connected to the electrodes. The magnitude and duration of the current pulse are determined by the total active resistance of the circuit and the inductance of the wires.

A disadvantage of the device is its low efficiency due to significant energy losses in the power supply circuits, low arc resistance and high discharge current, as well as a small volume of gas heated by the plasma of the arc. According to our estimates, the coefficient of conversion of electric energy into sound does not exceed 0.02%.

The aim of the invention is to increase the efficiency of an arc electro-acoustic transducer.

This goal is achieved by the fact that in an electro-acoustic transducer containing a discharge chamber with two electrodes, a capacitor charged from an external current source, and a pulse transformer, the primary winding of which is connected to the ignition pulse source, an inductance coil is introduced into the arc discharge circuit connected in series with a high voltage winding of a pulse transformer and a discharge chamber with two electrodes. The discharge chamber is made in the form of a hollow cylinder placed in the magnetic field of the coil in conjunction with it, the electrodes in the discharge chamber are located radially at an angle to each other and are in a plane perpendicular to the axis of the cylinder.

The introduction of an inductance coil into the arc circuit and its series connection with the high voltage winding of a pulse transformer and a discharge chamber with two electrodes allows limiting the pulse current of the arc, increasing the duration of the discharge pulse and reducing losses in the power supply circuit.

The placement of the discharge chamber in the magnetic field of the inductor allows the use of a strong magnetic field arising from the main discharge current in the coil to move the arc inside the discharge chamber during its combustion.

The location of the electrodes at an angle to each other in a plane perpendicular to the vector of the magnetic field of the coil provides an increase in the length of the arc cord (plasma) when moving it. This increases the efficiency of heat transfer between the plasma of the arc and the neutral gas in the discharge chamber, which allows to increase the efficiency of the converter.

In FIG. 1 is an electrical schematic diagram of a device; on fig

2 - arrangement of electrodes in a discharge chamber.

The electro-acoustic transducer (Fig. 1) comprises a discharge chamber 1 with two electrodes 2, a capacitor 3, a pulse step-up transformer 4, an inductor 5 and a shunt capacitor 6 thereof.

The discharge chamber 1 is connected in series with its two electrodes 2 in series with a capacitor 3 through a secondary (boost) winding of a pulse transformer 4 and an inductor 5. Shunt capacitor 6 connected

5 parallel to the inductor 5, and the capacitor 6 is much smaller than the capacitor 3. The primary winding of the pulse transformer 4 is connected to the ignition pulse source

0 bit, Capacitor 3 is connected to the poles of an external DC source. The discharge chamber 1 is made in the form of a hollow cylinder and placed in the working area of the inductor 5, and the electrodes 2 in

5, in the form of pins, are inserted radially into the discharge chamber 1 at an angle so that the magnetic field of the inductor 5 is directed perpendicular to the plane of arrangement of the electrodes 2, and the minimum distance

0 between the electrodes 2 is located in the central part of the chamber 1 (Fig. 2).

Electro-acoustic transducer operates as follows.

The capacitor 3 is charged periodically between the pulses of the arc discharge from an external source to a voltage of about 500 V, after which an ignition pulse of about 0 s is supplied to the primary winding of the pulse transformer 4. Moreover, on

a secondary voltage pulse of 15 3 kV occurs in the secondary winding of the pulse transformer 4, causing a spark breakdown of the gap between the electrodes 2 in the central part of the discharge chamber 1, where the distance between the electrode 2 is minimal. The capacitor 6 shunts the inductor 5 during the action of the ignition pulse. During the spark ignition discharge, a conductive channel is formed between the electrodes 2, through which the discharge of the capacitor 3 (main discharge) begins through the secondary winding of the pulse transformer 4 and the inductor 5. The gas discharge between the electrodes 2 quickly passes into the arc stage. The core of transformer 4 is saturated with main discharge current. An oscillating circuit is formed in the arc circuit, consisting of an inductor 5 and

capacitor 3, the resonant frequency of which is close to the frequency of the generated oscillations. The duration of the current pulse of the main discharge corresponds to half the period of free oscillations of this circuit. The arc cord 5 in the circuit containing the inductor 5 is resistant to short-term external influences. Therefore, deformation of the cord does not lead to arc breakage. This allows you to place 10 electrodes 2 in the discharge chamber 1 so that when the arc moves in the magnetic field of coil 5, the length of the arc cord increases significantly,

Under the action of the magnetic field of coil 15, each element of the arc discharge cord moves from the center of chamber 1 in the radial direction, preserving the shape of a circular arc. An extension of the arc discharge cord increases its electrical resistance 20 and, consequently, the amount of heat released in the discharge chamber 1 increases. The strong magnetic field of coil 5 causes the arc cord to move at high speed and sharply increases heat transfer in the region of the moving plasma. Pulse heating and rapid cooling of the gas in the discharge chamber 1 after the discharge ceases to generate a sound wave propagating from the device 30.

+ 0

The frequency of sound vibrations is equal to the repetition rate of the ignition pulses. The relative power level of the higher harmonics does not exceed 30% at a total acoustic power of 10 W,

The efficiency of the converter (according to the results of preliminary tests) is from 1 to 6%.

The transducer can be used in systems of acoustic and radio-acoustic sounding of the atmosphere, for vibration testing of structures in a gas medium and gas flow, for acoustic research of pipelines, mines, wells, and the like.

Claims (1)

The claims An electro-acoustic transducer comprising a discharge chamber with two electrodes, a capacitor, a pulse transformer with a high-voltage winding and an external current source, characterized in that, in order to increase the efficiency, an inductor is connected to it, connected in series with the capacitor and connected to one of electrodes, another electrode is connected to a high-voltage winding of a pulse transformer, moreover, the electrodes are located at an angle to each other in a plane perpendicular to the axis of the coil, and placed in its working th zone.