SU1630856A1 - Ultrasonic transducer - Google Patents

Abstract

This invention relates to an ultrasonic measuring technique. The purpose of the invention is to increase reliability at high temperatures. The converter comprises a housing 1, a piezoelectric element 2, the working and rear surfaces of which are connected by means of intermediate adhesive layers 3 to the protector 4 and the damper 5, respectively. The spring 6 is pressed against the damper by the cover of the housing 7. The insulating sleeve 8 contacts the inner surface of the housing. High-frequency connector 9 and all of the above elements are located in the housing coaxially. The galvanic connection of the surfaces of the piezoelectric element with the damper and protector is carried out by means of metal woven grids, the thickness of which is equal to the thickness of the corresponding intermediate adhesive layers, which are a silicate composition. When powering the piezoelectric element 2, its vibrations are transmitted through the protector to the controlled medium. 2 Il. J

Description

The invention relates to a measuring technique and can be used, for example, when measuring flow rates by an ultrasonic method.

The aim of the invention is to increase reliability at high temperatures.

FIG. 1 shows a converter, in FIG. 2 shows section A-A in FIG. one.

The converter includes a housing 1, in which the piezoelectric element 2 is coaxially arranged, whose working and rear surfaces are connected by means of intermediate adhesive layers 3 to the protector 4 and damper 5, respectively, spring 6, pressed against damper 5 by housing cover 7, insulating sleeve 8, located coaxially to housing 1 and adjacent to its inner surface, high-frequency connector 9, which provides a supply of electrical voltage to the electrodes of the piezoelectric element.

The galvanic connection of the working surface of the piezoelectric element 2 with the metal protector 4 is carried out using protrusions (weft) of a woven metal mesh, the thickness of which is equal to the thickness of the intermediate adhesive layer (Fig. 2). The protector can be made in one piece with the transducer case (welded joint) or connected to it through a thread. The electrical connection of the back surface electrode of the piezoelectric element 2 and the high-frequency connector 9 is carried out through a woven metal mesh installed in the intermediate adhesive layer 4 adjacent to the back surface piezoelectric element. The damper can be made of metal and non-metal. The solid acoustic contact thus obtained requires pressing the connection of the transducer elements, which is done by means of a spring 6 and a cover of the housing 7

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at a pressure of 15-50 kg / cm2 to further exclude possible delamination. The insulating sleeve 8 is intended to isolate the woven metal mesh from the transducer housing 1 when it protrudes along the outer perimeter, as well as in the case of using a metal damper. Intermediate adhesive layers are a silicate composition.

The proposed Converter is as follows.

The protective cup formed by the connection of the case 1 and the tread 4 by welding is made of titanium brand VTZ-1, the thermal coefficient of linear expansion of which is 9 10e.

The adhesive composition (cement bond) is made of an aluminosilicate binder and barium ferrite powder as a filler. The thermal coefficient of linear expansion of cement is (10-14) "106. The thermal coefficient of linear expansion of piezoelectric ceramics, for example, PZT-26, is (4.5-7.5) 40 6.

This factor for a woven metal mesh, such as nickel steel, is 7.9106 degrees D The wire diameter is chosen to be 0.6-0.7 mm when selecting quarter-wave thickness of intermediate adhesive layers at the resonant frequency of the converter 1.5 MHz.

The Converter operates as follows.

When a working impulse is applied to the lighter element 2, the sound wave through the intermediate adhesive layer 3 and the protector 4 goes into the controlled medium. From the back of the piezoelectric element 2 is a sound wave, the passage through the intermediate adhesive layer 3, with

It is a damper 5, where it is quenched. At the borders of the piezoelectric element — an intermediate adhesive layer — a protector and a piezoelectric element — an intermediate adhesive layer — the reflection damper will be insignificant, since the impedance of the metal mesh is close to the impedance of the piezoceramics. The implementation of solid acoustic contact with an adhesive composition reinforced with a metal grid ensures the resistance of the transducer elements to cyclic temperature differences, since the intermediate adhesive layer, the piezoelectric element and the protector have thermal coefficients of linear expansion in one order.

Claims (1)

Invention Formula An ultrasonic transducer comprising a housing and a piezoelectric element coaxially disposed therein, a damper, a protector, a spring, an insulating sleeve, a high-frequency connector, the protector and the damper being connected to the working and back sides of the piezoelectric element respectively, the insulating sleeve contacts the inner surface of the housing, and the spring is located between the damper and the movable housing cover, characterized in that, in order to increase reliability at high temperatures, the intermediate adhesive layers are made in the form a silicate adhesive composition, and between the surfaces of the piezoelectric element and the surfaces of the damper and protector facing them, woven metal grids are installed, the thicknesses of which are equal to the thicknesses of the intermediate adhesive layers located respectively between the surfaces of the damper, piezoelement and protector. one Phie.1 Aa i FIG. g