SU1534408A1 - Fiber-optic sensor of vibration accelerations - Google Patents

Abstract

This invention relates to a measurement technique and can be used in vibration sensors. The purpose of the invention is to expand the frequency range of controlled movements by changing the stiffness of the elastic suspension. The light flux from the source enters the sensitive element 2, made in the form of mutually perpendicular intersecting turns of optical fiber, the number of which is the same in both directions. When exposed to vibration acceleration W _{O, the} inertial curvature of the mass 3 of the sensor deflects a change in the radius of curvature of the optical fiber helix, which leads to a change in the intensity of the light flux and, consequently, an electrical signal at the output of the sensor. The shape of the sensing element provides the same stiffness of the elastic suspension in the working and transverse directions, which provides an increase in the resonant frequency in the transverse direction, and thereby expand the frequency range of the sensor. 3 il.

Description

This invention relates to a measurement technique and can be used in vibration sensors.

The purpose of the invention is to expand the frequency range of controlled oscillations by changing the stiffness. elastic suspension.

FIG. 1 shows a block diagram of a fiber-optic vibration sensor; in fig. 2 - frequency characteristics of the sensors; in fig. 3 - order of assembly of the sensitive element of the sensor.

The sensor comprises a housing 1, a sensing element 2 in the form of a light-guide spiral from mutually perpendicular intersecting turns, the number of which is the same in both directions, and an inertial mass 3.

The sensor works as follows.

Luminous flux from the source (not

shown) is fed to the input of the sensing element 2, passes through the spiral of the optical fiber and at the output of the sensing element 2 in a photodetector (not shown) is converted into an electrical signal. When subjected to vibration acceleration, the inertial mass of the sensor deviates and causes a change in the radius of curvature of the fiber optic coil, resulting in a violation of the total internal reflection of the light flux in the optical fiber, which leads to the measurement of the intensity of the light flux and, consequently, the electric signal at the output of the sensor.

The resonant frequency of the transducer design in the transverse direction is largely shifted compared to the known sensor (Fig. 2a) towards the main resonance (Fig. 2b

Since the rigidity of the mechanical system of the elastic suspension sensor) is almost the same in the working and transverse directions, due to the equal number of turns of the sensing element in both directions and their identical arrangement.

Thus, the proposed form of the sensing element allows

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Dust the resonant frequency in the transverse direction and thereby significantly expand the frequency range of the sensor.

The sensing element can be assembled, for example, as follows (Fig. 3).

The casing 1 and the inertial ма-masse 3 are slotted (FIG. 3a). The width of the slot corresponds to the diameter of the fiber. The case and the inertial mass are glued with an easily soluble glue on the holders A and Fixed in a clamp towards each other with a gap H, which is provided with a gasket K (Fig. 36). The value of H corresponds to the diameter of the bend of the fiber. The diameter of the bend, as well as the number of turns, is determined experimentally.

The fiber is laid in the grooves as shown in FIG. Sound The grooves are filled with glue. Then, parts 1 and 2 are glued from holders A.

Such an assembly ensures that the parameters of the sensing element are identical in the manufacture of sensors.

The technical solution can also be implemented in a differential sensor of vibration accelerations, which contains two sensitive elements, similar to these, associated with the inertial mass located between them and connected at the output of the photodetector towards each other. The use of a differential circuit allows to increase the sensitivity of the sensor by 2 times and reduce the measurement error while simultaneously expanding the frequency range.

Claims (1)

Invention Formula A fiber-optic vibration acceleration sensor, comprising a housing, a sensitive element in the form of a light-guided spiral and an inertial mass, characterized in that, in order to expand the frequency range of monitored oscillations, the sensitive element is made in the form of mutually perpendicular intersecting turns, the number of which is the same in both directions x. I "J " L 4 f W W ABOUT " I " WW FM / .t / fj) Compiled by S. Grachev Editor V. Petrash Tehred MLidyk Order 39 Circulation 441 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5 W / "V Ј4 / L one / I / I Yg-gay  7L l .J Proofreader S. Shekmar Subscription