SU957323A1 - Piezoelectric converter of bendtng deformation to electric sigm - Google Patents

Description

(54) PIEZOELECTRIC CONVERTER OF BENDING DEFORMATIONS TO ELECTRIC SIGNAL

one

The invention relates to measuring equipment, namely, devices for measuring parameters of vibrations, vibrations of the soil, machines and mechanisms.

Known piezoelectric transducer bending deformation, which consists of two glued piezoceramic plates. Between the piezoceramic plates often place a plate of elastic material 1.

The closest to the proposed technical essence is a piezoelectric transducer of bending deformations into an electrical signal, made in the form of a piezoceramic plate with electrodes on the main surfaces fixed in the housing. The piezoceramic plate is attached to an elastic membrane, Le 2.

The sensitivity of the known flexural-vibration transducers is low and depends on where the so-called neutral layer is located. The closer the neutral layer is to the axis of symmetry of the piezoelectric element, the lower the sensitivity, which

also depends on the thickness and elastic properties of the membrane and piezo-ceramic plate.

In addition, the design of the active element is multi-layered. Most often, piezoelectric elements are assembled into a bimorph or multilayer structure using glue, while the sensitivity and strength of the transducers will decrease with increasing thickness of the glue layer. The voids and air bubbles in the adhesive layer also have a negative Q effect on the parameters of the converter.

The sensitivity of a transducer, such as a beam, is inversely proportional to the thickness of the piezoelectric element, and with the existing technology of making bimorph 15 and multilayer bending vibration transducers, the transducer thickness cannot be less than 0.6 mm.

The purpose of the invention is to increase the sensitivity and simplify the design.

The goal is achieved by the fact that

Claims (2)

20 in a piezoelectric transducer of bending deformations into an electrical signal, made in the form of a piezoceramic plate with electrodes on the main surfaces fixed in the housing, the electrodes of the piezoceramic plate are divided into two identical sections and form two sections of the transducer with opposite polarization direction. The electrodes of each section are electrically interconnected. The presence of two sections in the active element of a transducer with polarization having a direction made it possible to register bending vibrations from a monolithic plate, i.e. two or multi-layer, .. -j --- - active element for bending vibration receivers is proposed to be replaced by two-piece. Compared with bimorph, a two-section receiver is two or more times thicker, which gives a gain in sensitivity in the simplest case of a receiver in the form of a beam rigidly fixed from one end: and free on the other, two or more times. The manufacture of monolithic piezoelectric plates instead of bimorphs does not lead to any new additional technological operations. The sectional deposition of electrodes is known and simple. The absence of the operation of connecting the piezoelectric elements into the bimorph sokrats; there is a technological chain of manufacture, the manufacturing labor intensity is reduced, and the percentage of usable products increases. FIG. 1 shows the proposed converter; in fig. 2 is a disk transducer rigidly fixed along the contour, the electrodes of which are divided by diameter; in FIG. 3-5 - a converter in the form of a plate, rigidly fixed from two parallel sides, free from the other two, three options for separating the electrodes into symmetric ones: longitudinal, transverse, diagonal. The converter 1 is divided into two sections 2 and 3, having polarization of different direction (the direction of the polarization vectors is indicated by arrow), two electrodes 4 of section 1, as well as electrodes 5 of section 2, can be interconnected. The Converter bending deformations works as follows. Under the action of a bending mechanical load, the piezoceramic plates are deformed, the upper fibers are stretched and the lower ones are compressed, and since sections 2 and 3 are polarized in opposite directions on the electrodes 4 a charge of one sign is generated, and on the electrodes 5 of the other. The connection electrodes as shown in FIG. 1, it is possible to register an electrical signal proportional to the actual bending strain. The division of the electrodes into two symmetric and equal in area is made depending on the method of mounting the converter in the receiver housing. With a symmetric fixing, for example, with a rigid fixing around the contour, the distribution of the generated charge over the area of the active converter is also symmetrical. In this case, possible longitudinal, transverse and diagonal division of the electrodes. With asymmetrical fixing, for example a beam, one end of which is free and the other rigidly fixed, there is a preferred longitudinal separation of the electrodes. Most often, in the receivers of mechanical oscillations, the transducer is rigidly fixed along the entire contour, or two parallel sides are fixed. The proposed converter for recording low-frequency signals, in view of monolithic fabrication, can be used both for recording very high levels of signals and for low-power ones. When registering powerful signals mechanically., -. The strength of the proposed receivers increases significantly due to the absence of an adhesive layer. When registering weak signals, the active element can be made very thin, according to the existing domestic technology, the minimum thickness of the piezoelectric element is h 0.33 mm. Laboratory tests of two variants of the proposed converter were carried out. In the first embodiment, the transducer has geometrical dimensions of 30 X 5 X 1 mm. The converter is rigidly fixed at one end, and at the other end a variable force acts F FO to.ti With the same driving force, the output voltage of the bimorph is 0.18 V, and the proposed receiver is 0.42 V. In the second variant, the disk the receiver 40 x 1 mm is rigidly fixed along the contour. The plate is divided into two sections by diameter. Exciting force is applied to the center of the plate. Under all the same conditions of excitation and registration of the output voltage of the prototype, it is 0.025 V, and in the proposed converter 0.32 V. It should be noted that in the proposed sensing element its own electrical capacitance decreases compared to the prototype. However, this does not lead to difficulties in matching the element with subsequent electrical circuits if it is connected to the input of an emitter follower with a large input resistance of -5-10 GΩ. The use of the proposed piezoelectric transducer bending deformations into an electrical signal increases the sensitivity in the range of operating frequencies by 2-10 times while simplifying the design and increasing mechanical strength compared to bimorph. It can be used in receivers measuring various physical quantities: speed, acceleration, deformation, hydroacoustic and acoustic pressure. Claim 1. Piezoelectric transducer of bending deformations into an electrical signal, made in the form of a piezo-ceramic plate with electrodes on main surfaces, fixed in the housing, characterized in that, in order to increase the sensitivity and simplify the design, the electrodes of the piezoceramic plastic w. / J fug. The two of us are divided into two identical sections and form the Ave sections of the converter with the opposite direction of polarization. 2. Converter according to claim 1, characterized in that the electrodes of each section are electrically interconnected. Sources of information taken into account in the examination of 1- Ultrasonic transducers. Ed. Kikuchi. M., “Peace, 1972, p. 258. 2. Pressure transducers of the Research Institute of Mechanics and Applied Mathematics, Rostov-on-Don State University, Rostov-on-Don University Press, 1976 (prototype). F1 / g.