RU2309435C1 - Piezo-electric bending transformer with controllable resonance frequency - Google Patents

Abstract

FIELD: technology for registering seismic oscillations of soil and vibration.

SUBSTANCE: piezo-electric bending transformer with controllable resonance frequency contains two piezo-ceramic elements, and also two bushings with right and left thread respectively, and adjusting pin passing through them, while one ends of both piezo-ceramic elements are rigidly held between each other, and other ends are fastened to corresponding bushings, or each piezo-ceramic element and corresponding bushing are made as single whole structural element.

EFFECT: possible expansion of working band of frequencies without structural changes directly during measurements.

3 cl, 1 dwg

Description

The invention relates to measuring devices and can be used to record seismic vibrations of the soil and vibration.

Cantilever-type piezoelectric transducers are known, which are a piezoelectric plate (bimorph), one end of which is rigidly fixed to a solid base (BOSH Acceleration seusors, p.20-22) (US Patent 4700973) (Yanchich V.V. Piezoelectric accelerometers based on a monolithic block with bending deformation. Foreign Radio Electronics, 9, 1996, pp. 63-64).

Piezoelectric sensors are known in which to eliminate the influence of the resonant frequency, liquid is used as an inert mass (RF Patent No. 2129290), bulk materials, or both, taken in a certain ratio (RF Patent No. 21117966).

The disadvantage of these devices is the inability to expand the working frequency band without significant design changes.

The closest in technical essence to the proposed one is a piezoelectric geophone according to the patent of the Russian Federation No. 2204850, G10V 1/16, publ. 06/20/2003, adopted as a prototype.

The prototype seismic receiver contains a housing, a piezoelectric bending element consisting of a piezoceramic plate and a metal membrane, as well as two air cavities, an air channel.

The prototype device works as follows.

Oscillations of the object of study are transmitted to the body rigidly connected to it. Inertial phenomena lead to a bend of the piezoelectric element, which converts mechanical vibrations into an electrical signal. Air closed in the cavities, due to its elasticity, prevents bending vibrations. In the presence of an air channel between the cavities, air from the volume in which the compression takes place flows into the rarefaction cavity. Air cavities connected by a channel are an acoustic resonant unit in which at a certain frequency a resonance arises of the air mass concentrated in the cavities and the air mass concentrated in the channel.

By choosing the dimensions of the cavities and the channel, it is possible to shift the resonant frequency of the acoustic unit relative to the resonant frequency of the piezoelectric element and thus control the frequency response of the geophone as a whole. To expand the working frequency band of the seismic receiver, it is necessary to ensure the equality of the resonant frequencies of the piezoelectric element and the acoustic unit, including the cavity and channel. In this case, a certain relationship should be fulfilled between the geometric, mechanical and acoustic parameters of the elements of the seismic receiver, i.e. To change the frequency response, changes in receiver design are necessary.

The disadvantage of the prototype device is the inability to expand the working frequency band without significant structural changes.

To eliminate these drawbacks, a second piezoceramic element, as well as two bushings with right and left-hand threads, respectively, and an adjustment pin passing through them, respectively, are inserted into a piezoelectric bending transducer with an adjustable resonant frequency, and the ends of both piezoelectric elements are rigidly fixed between by itself, and the other ends are attached to the corresponding bushings, or each piezoceramic element and its corresponding sleeve is made They are as one whole structural element.

In this case, a piezoceramic plate glued to a flexible plate or bimorph is used as a piezoceramic element.

The drawing shows the proposed device, where it is indicated:

1 - piezoceramic element;

1.1 - piezoceramic plates (or bimorphs) of the cantilever type;

1.2 - flexible plates;

3 - bushings;

4 - an adjusting hairpin.

The proposed Converter contains two piezoelectric elements 1, each of which consists of a piezoceramic plate (or bimorph) of the cantilever type, glued to a flexible textolite or metal plate 1.2. In this case, one ends of both piezoelectric ceramic elements 1 are rigidly fixed to each other, other ends are fixed to two bushings 3 (the corresponding bushings and piezoceramic elements 1 can be made as one whole structural element). In this case, one of the bushings 3 has a right and the other left thread. An adjustment pin 4 passes through the bushings 3, during rotation of which the angle α between the piezoceramic elements 1 changes.

The converter operates as follows. Vibration from the object or seismic vibrations cause the piezoelectric elements 1 to bend, which leads to the appearance of an electric charge proportional to the external force acting on them. Rotating the adjustment pin 4, we increase the angle α between the piezoceramic elements 1 and thereby increase the rigidity of the system in the direction of the sensitivity axis.

This increases the resonant frequency and extends the operating range of the converter, without requiring a change in the design of the device, as in the prototype.

The technical result of the proposed device is the expansion of the operating frequency band in the measurement process without changing the design and weight and size parameters of the Converter.

In addition, as a result of testing the prototype, the following advantages of the proposed device were identified:

- increase the vibration stability and impact resistance of the Converter;

- elimination of technological errors in the manufacture of elements and components of the converter and its mounting on the object;

- the ability to compensate for temperature drift;

- decrease in sensitivity to vibrations that do not coincide with the sensitivity axis of the transducer.

Claims (3)

1. A piezoelectric bending transducer with an adjustable resonant frequency, comprising a piezoceramic element, characterized in that a second piezoceramic element is introduced, as well as two bushings with a right and left thread, respectively, and an adjustment pin passing through them, with one end of both piezoceramic elements being rigidly fixed between by itself, and the other ends are attached to the corresponding bushings, or each piezoceramic element and its corresponding sleeve are made as one whole structural element ment. 2. A piezoelectric bending transducer with an adjustable resonant frequency according to claim 1, characterized in that a piezoceramic plate glued to a flexible plate is used as a piezoceramic element. 3. A piezoelectric bending transducer with an adjustable resonant frequency according to claim 1, characterized in that a bimorph is used as a piezoceramic element.