SU1731291A1 - Compound electroacoustic flexural vibration transducer - Google Patents

Abstract

This invention relates to ultrasound instrumentation. The purpose of the invention is to reduce the longitudinal dimensions of the converter while maintaining the fundamental resonant frequency. The converter contains a curvilinear resonator with a cavity and a fastener, a piezoelectric element fixed with tension in the cavity of the resonator. All centers of curvature of the internal surface of the resonator are located on one side of the plane of the cross section of the resonator passing through the mechanical displacements of the node. The fastening element and the cavity with the piezoelectric element fixed in it are placed on opposite sides of this plane. The fastener is located inside the resonator, and the piezoelectric element is installed perpendicular to the longitudinal axis of the resonator. When voltage is applied to the piezoelectric element, it makes longitudinal oscillations that are transmitted to the resonator exciting bending oscillations in it

Description

The invention relates to ultrasound instrumentation and can be used in impedance-sensitive and receiving-emitting ultrasound control systems.

Known composite piezoelectric transducer rod-type, containing a cavity in the acoustic resonator. The transducer contains piezoceramic plates, back plates and an average liner with a system of holes.

The main drawback of the device is the small mechanical quality factor caused by the presence of gluing.

A rod-type electroacoustic transducer is known that contains a monolithic acoustic resonator with a cavity and a fastener located in the region of the mechanical displacements of the resonator, and a piezoelectric element fixed with a tension in the cavity cavity along the surface partially coupled to the walls of the cavity, the resonator, the piezoelectric cavity and the fastening the element is made symmetrical with respect to the plane of the longitudinal axial section of the resonator

The absence of adhesive joints can significantly increase the quality factor of the composite electroacoustic converter.

The drawback of the device is a large size along its longitudinal axis at a given basic resonant frequency of the converter.

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The purpose of the invention is to reduce the longitudinal dimensions of the transducer while maintaining the fundamental resonant frequency.

This goal is achieved due to the fact that in a composite electroacoustic transducer containing a monolithic acoustic resonator with a cavity and a fastener located in the region of the mechanical displacement of the resonator, and a piezoelectric element fixed to the surface partially conjugated with the cavity wall, moreover, the resonator, cavity, piezoelement and fastener are made symmetrical relative to the plane of the longitudinal axial section of the resonator, the resonator is made of curvolines Yunny, all the centers of curvature of its inner surface are located on one side of the cross-sectional plane passing through the mechanical displacements knot, the fastener and the cavity, with the piezoelectric element fixed in it, are placed on opposite sides of the resonator's cross-sectional plane mechanical displacements, the fastening element is located on the side of the inner surface of the resonator, and the piezoelectric element is installed perpendicular to the longitudinal axis of the resonator.

FIG. 1 shows a composite electroacoustic flexural vibration transducer; FIG. 2 is a section A-A in FIG. 1.

The converter contains a monolithic resonator 1 with a cavity 2, located in the nodal region of mechanical displacements of the resonator, and a piezoelectric element 3 fixed in this cavity. Acoustic contact between the resonator 1 and piezoelectric element 3 is carried out along the mating surfaces of the projections 4 of the cavity 2 due to tension. The tension is provided by the choice of the dimensions of the cavity, the protrusions and the size of the piezoelectric element. The fastening element 5 located in the nodal region of the mechanical displacements of the resonator 1 and made integral with it, allows it to be fixed, for example, to the housing, without significantly reducing the mechanical quality factor of the converter.

Resonator 1 is made curvilinear, all curvature centers (for example, SI, 02, Oz) of its inner surface are located on one side of the plane BB of the cross section of the resonator passing through the mechanical displacements node. The fastener and the cavity, with the piezoelectric element fixed in it, are placed along

different sides of the plane bb. In this case, the fastening element 5 is located on the side of the inner surface of the resonator, and the piezoelectric element 3 is installed perpendicular to the longitudinal axis of the resonator 0-0.

Acoustic resonator 1 can be made of any solid material with low sound absorption (metal, glass, ceramics) and be bell-shaped, horn-shaped or U-shaped.

The cross section of the cavity 2 of the cavity may be round, square, rectangular, oval, etc. The piezoelectric element 3 can be made of any piezoactive material, for example, piezoceramic or single crystal, in the form of a plate of rectangular, round, oval or square shape. The fastening element 5 can be made in the form

solid or hollow rod of rectangular or circular cross section, and also in the form of a flange. Moreover, the resonator, the cavity, the piezoelectric element and the fastening element must be made symmetrical with respect to

the plane of the longitudinal axial cross section of the resonator in order to avoid the occurrence of parasitic oscillation modes in the resonator and a decrease in its quality factor.

The converter works as follows.

in a way.

A piezoelectric element 3, installed in a band and 2 of a monolithic resonator 1, when applied to it by an alternating electrical voltage, makes mechanical oscillations

in their own plane, which, through acoustic contact with the protrusions 4, provided with tension, are transmitted to the acoustic resonator 1. If the frequency of the exciting electrical voltage coincides with

due to the large acoustic quality factor, flexural wall oscillations occur in the natural resonant frequency of the acoustic resonator 1, which leads to the emission of acoustic waves into the environment surrounding the converter.

The proposed electroacoustic transducer is reversible and can also be used to receive acoustic oscillations from the surrounding

environment.

Claims (1)

Claims of the Invention A composite electroacoustic flexural vibration transducer comprising a monolithic acoustic resonator with a cavity and a fastening element located in the region of the mechanical displacement of the resonator assembly and a piezoelectric element fixed with a tension in the cavity of the resonator along the surface partially coupled to the cavity wall. the cavity, the piezoelectric element and the fastening element are made symmetrical relative to the plane of the longitudinal axial section of the resonator, characterized in that, in order to reduce Given the longitudinal dimensions of the converter while maintaining the fundamental resonant frequency, the resonator is curved, all the centers of curvature of its inner surface are located on one side of the plane of the transverse cross section. In addition, a fastening element and a cavity with a piezoelectric element fixed in it passing through the node of its mechanical displacements are placed on opposite sides of the plane of the cross section of the resonator passing through the node of its mechanical displacements, the fastening element is located on the side of the internal surface of the resonator, and the piezoelectric element is installed perpendicular to the longitudinal axis of the resonator. " /////// 77 ABOUT Riga.1 "Fff, j, h