RU2382990C1 - Detector of mechanical oscillations - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: invention is related to detectors of mechanical oscillations, in particular to detectors of vibrations or detectors of accelerations. Detector of mechanical oscillations includes body with several piezoceramic plates inside, which are installed on body walls in a cantilever manner. Three pairs of piezoceramic plates are installed in mutually perpendicular planes, at the same time plates of each of pairs are installed in a cantilever manner on opposite sides symmetrically versus planes of other pairs arrangement.

EFFECT: provision of simultaneous measurement of linear oscillations in arbitrary direction versus detector and rotary mechanical oscillations in space versus arbitrary axis.

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Description

Technical field

The invention relates to sensors of mechanical vibrations, in particular to vibration sensors or acceleration sensors.

State of the art

A known mechanical vibration sensor, Japanese patent application JP 57139664, published on 08/29/1982, comprising a housing with several piezoceramic plates inside mounted cantilever on the walls of the housing with the ability to connect to an external device for processing electrical signals generated by bending of piezoceramic plates.

This known sensor does not provide for the detection and measurement of rotational mechanical vibrations and linear mechanical vibrations in an arbitrary direction relative to it.

Disclosure of invention

The technical result achieved in the claimed sensor of mechanical vibrations consists in the ability to simultaneously detect and provide measurements of linear vibrations (accelerations) in an arbitrary direction relative to the sensor and rotational mechanical vibrations (angular accelerations) in space relative to an arbitrary (any) axis (sensor).

The specified technical result is achieved in a mechanical vibration sensor, including a housing with several piezoceramic plates inside, mounted cantilever on the walls of the housing with the ability to connect to an external device for processing electrical signals generated by bending of piezoceramic plates, while three pairs of piezoceramic plates are located in mutually perpendicular planes, the plates of each of the pairs (located in the same plane) are mounted cantilever from opposite sides (on the opposite bying walls of the housing) symmetrically relative to the plane of arrangement of other pairs.

The symmetric installation of a pair of piezoceramic plates in one plane allows the separation of signals caused by linear acceleration in the direction perpendicular to the plane of location of this pair and signals caused by angular acceleration during the rotational movement of the sensor (relative to an axis perpendicular to the longitudinal plane of symmetry of this pair) from a comparison of electrical signals . And the symmetry of each of the three pairs of piezoceramic plates relative to the two planes of the other two pairs perpendicular to them ensures the determination of linear acceleration and angular acceleration vectors, due to the independence of the signals of each pair of plates from the signals of other pairs of plates.

It is advisable to select (perform) piezoceramic plates with the same dimensions (parameters) and arrange them at the same distance from each other. This will ensure the uniformity of signals from each pair of plates with the same impact.

The installation of piezoceramic plates inside the housing allows you to protect the piezoceramic plates from external influences and provides unhindered installation of the sensor on the product, the mechanical vibrations (vibrations) of which must be detected or measured.

Piezoceramic plates may be bimorphic.

Piezoceramic plates can be installed in the grooves of the walls of the housing, made in the form of a hollow metal cube.

Brief Description of the Drawings

Figure 1 presents the arrangement of three pairs of piezoceramic plates in the housing.

Figure 2 presents the installation diagram of one of the pairs of piezoceramic plates in the housing.

Figure 3 and figure 4 presents a diagram of a device for detecting linear and / or angular acceleration using one of the pairs of piezoceramic plates.

The implementation of the invention

The principle of operation of existing piezoelectric sensors is based on measuring the projection of the linear acceleration vector onto the measuring axis of the sensor. However, it is important to know, firstly, the values of the linear acceleration vector, and secondly, the values of the angular acceleration vector of bending vibrations. The simplest example of the effect of bending vibrations is the rapid destruction of the wire during periodic bending.

According to the invention, a 6D mechanical vibration sensor is proposed, which allows simultaneously measuring in a small area, practically at a point, six components of the parameters of the wave mechanical field — three linear and three rotational accelerations. Knowing the six components of the vibration field at two neighboring points allows you to get the exact value of the stress-strain state in the material subjected to dynamic stress.

The sensor is a hollow body in the form of a cube (Fig. 1), in each face of which a sensing element is mounted - an ordinary or bimorph piezoceramic plate.

Plates 1 and 2 are fixed in the XY plane, and the other two pairs of plates in the XZ and YZ planes. The polarization of the opposite piezoelectric plates of each pair coincides in direction. The receiver body is rigidly mounted on the vibrating surface of the object.

The sensor works identically in all three coordinates, so consider its work in the direction of one of the axes. Figure 2 shows the location of the sensitive elements - plates 1 and 2, used to measure linear vibrations in the direction of the Z axis.

The sensor operates as follows. When the sensor is driven by translational oscillations along the Z axis, piezo plates 1 and 2 begin to bend due to the inertia of their own mass in one direction, opposite to the direction of acceleration of the sensor housing. The bend of the piezoelectric plates, shown in figure 3, causes the appearance of electrical signals of the same polarity on the electrodes of the piezoelectric plates. The same-polar signals + D _post 1 and + D _post 2, proportional to the translational acceleration of the sensor, after amplification by the preamplifiers 3 and 4, are fed to the adder 5. In this case, with linear vibration of the sensor along the Z axis, the signals on the adder will synchronously add up, and the measurement , with equal sensitivity of the plates, will be + 2D _post .

When exposed to angular acceleration around the Y axis, plates 1 and 2 will bend in opposite directions with respect to the Z axis. As follows from figure 4, bending vibrations cause the formation of equal signals of the opposite sign on the plates. Bipolar signals -D _rotate 1 and + D _rotate 2, proportional to the rotational movement of the sensor, after amplification by the preliminary amplifiers 3 and 4 are fed simultaneously to the adder 5 and the signal subtraction device 6, and we obtain the following result when the signals from the plates 1 and 2 are equal: the signal at the output of the adder will be zero, and the signal at the output of the subtraction device will double. In this case, during torsional vibrations of the sensor around the Y axis, the bipolar signals of plates 1 and 2 will be synchronously subtracted, and the measurement will be ± 2D _rotation .

Thus, with simultaneous translational and rotational vibrational movements of the sensor at the output of the adder, a signal proportional to the translational movement of the sensor in the Z axis direction is measured, and a signal proportional to the rotational movement of the sensor along the Y axis is measured at the output of the subtraction device.

The work on the other two axes Y and X of the receiver is similar, as shown in the table.

Table measurement sensing element type of measured impact summation subtraction progressive, along the axis rotational, about an axis Z Y X Y X Z 2D _Zpost 2D _Return 1Z + D _post 0 0 -D _rotation 0 0 2Z + D _post 0 0 + D _rotation 0 0 2D _Post 2D _hrv 3Y 0 + D _post 0 0 -D _rotation 0 4Y 0 + D _post 0 0 + D _rotation 0 2D _Xpost 2D _ZRV 5X 0 0 + D _post 0 0 -D _rotation 6X 0 0 + D _post 0 0 + D _rotation

The body material of the mechanical vibration sensor is stainless steel or titanium, or another durable material, not subject to low-frequency resonance, such as glass ceramics. For a six-component sensor, six housing walls with plates mounted on them can be mechanically fastened (screw fixing of the adhesive joint for low-frequency sensors, or welding for high-frequency sensors). The housing can also be assembled from three corners or two U-shaped walls, which increases the rigidity of the structure, but complicates the installation of the plates.

The cantilever design of the plate fastening is carried out by installing the plate in the slot (slot in the wall) of the housing with fixing using thermosetting polymers or mechanical threaded clamps. To simplify the procedure for adjusting the position of the plates in planes strictly intersecting in the center of the cube, you can pre-mount the plate in an insulating mandrel, which, in turn, can be more conveniently attached to the wall of the casing. To select the resonant frequency and sensitivity of the sensor on piezoceramic plates, cargo can be secured.

All piezoceramic plates are made with the same dimensions and equally fixed. Each pair of plates is polarized in the same direction.

Claims (4)

1. The sensor of mechanical vibrations, comprising a housing with several piezoceramic plates inside, mounted cantilever on the walls of the housing, characterized in that three pairs of piezoceramic plates are located in mutually perpendicular planes, while the plates of each pair are mounted cantilever from opposite sides symmetrically with respect to the other steam 2. The sensor according to claim 1, characterized in that the piezoceramic plates are bimorph. 3. The sensor according to claim 1, characterized in that all the piezoceramic plates are made with the same dimensions and are installed at the same distance from each other. 4. The sensor according to claim 1, characterized in that the piezoceramic plates are installed in the grooves of the walls of the housing, made in the form of a hollow metal cube.

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