CN101191751A - A torque fiber optic sensor - Google Patents

Abstract

The invention relates to the design of a novel torque optical fiber sensor, which belongs to the field of testing technology and optical fiber sensor. The present invention uses long-period fiber grating or fused-taper fiber as the measuring element, when the long-period fiber grating or fused-taper fiber is subjected to torque, the period of the long-period fiber grating or the light intensity or spectrum of the fused-taper fiber changes, thereby measuring torque value. The sensor is composed of guiding optical fiber, torsion rods (2), (3), long-period optical fiber grating or conical optical fiber (5), and spring (4). Wherein, the two torsion bars (2) and (3) are connected by a spring (4), and the torsion bar (2) and the torsion bar (3) can rotate. Long-period fiber gratings or fused cone fibers for sensing are respectively fixed on the two torsion bars (2) and (3). In addition, a magnet is installed on a torsion bar of the torque sensor, together with a magnet with opposite polarity installed on the rotating mechanism, an optical fiber speed sensor based on torque measurement can be formed.

Description

A torque fiber optic sensor

technical field

The invention belongs to the field of testing technology and optical fiber sensors, and in particular relates to the design of a novel torque optical fiber sensor and a scheme for realizing the design principle.

Background technique

In the mechanical transmission system, torque is one of the most typical mechanical quantities that reflect the performance of the production equipment system. Torque measurement and analysis are important means to ensure the safe and normal operation of various production and auxiliary equipment, save energy, and improve system efficiency. Improving the accuracy of torque measurement, the real-time performance of torque monitoring and control, and the reliability of torque abnormality analysis is an important means to reduce accidents and make production go on normally.

With the advancement of science and technology and the development of production, torque measurement technology has broad application prospects. At the same time, the monitoring of torque has also put forward higher and higher requirements: from static test to dynamic online detection; from indirect measurement to direct measurement; from single function to multi-function, including self-compensation, self-correction, self-adaptation, self-diagnosis , remote setting, state combination, information storage and memory; require system miniaturization, digitization, intelligence, virtualization and networking; require the combination of torque detection and power device control to achieve the optimization of speed, torque and output power configuration.

The current torque sensors mainly include strain type, magnetoelectric phase type, and photoelectric type. They have the disadvantages of requiring a special elastic shaft, two shaft couplings for installation, complex structure, small torsional strain of the elastic shaft, and affecting the sensitivity. In addition, in the design of the torque sensor, the main problems lie in the manufacture, selection, installation, etc. of the sensitive components. The commonly used torque sensor uses a piezoelectric quartz wafer as the measuring element. This kind of sensor requires a large number of piezoelectric quartz wafers. The height of the wafer and the flatness and roughness of the contact surface are very strict. The processing is difficult and the process requirements are high.

Contents of the invention

The purpose of the present invention is to overcome the defects of troublesome, complicated and low-precision testing in the traditional measuring method, and to invent a new optical fiber torque measuring method and a new sensor, so that the measuring operation is simple, the cost is low, the precision is improved, and the measuring range is expanded. And anti-electromagnetic interference. This method has the characteristics of high measurement accuracy, superior all-optical properties, insulation, explosion-proof, anti-electromagnetic interference, and high-temperature resistance. It is suitable for the measurement of the dynamic characteristics of the transmission system of large machinery under high temperature, explosion hazard and strong electromagnetic interference and other harsh environments.

The technical scheme adopted in the present invention is as follows:

The invention includes guiding optical fiber, two torsion bars, a section of sensing optical fiber and a spring. The two torsion bars are connected by springs; the sensing optical fibers pass through the central axes of the two torsion bars and are respectively fixed at the ends of the two torsion bars. Among them, two torsion bars are connected by springs. The role played by the spring is not only the connection function, but also the reset function, that is, when there is no relative rotation between the two torsion bars, the spring can ensure that the two torsion bars are at the initial position. In addition, when the torque applied to the torsion bar is removed, the spring can ensure that the torsion bar returns to the initial position, realizing repeated measurements.

In this sensor structure, when the torsion bar rotates under the action of force, the sensing fiber is also twisted under the action of torque. The light intensity or wavelength change of the transmission spectrum after the sensing fiber is twisted is related to the magnitude of the torque. By measuring the light intensity or wavelength change of the transmission spectrum of the sensing fiber, the torque value can be obtained.

Compared with the prior art, the present invention has the following advantages:

1. It adopts all-fiber structure, which can effectively prevent electromagnetic interference and can be used in dangerous working environments;

2. The measurement element adopts long-period fiber grating or fused tapered fiber, and the torque is measured by using the light intensity or wavelength change of the transmission spectrum after the sensing fiber is twisted, which can realize high-precision measurement;

3. The scheme is simple in structure, easy to install, and can have lower cost than ordinary torque sensors;

4. The scheme can realize distributed measurement, which is not available in traditional sensors.

Description of drawings

Fig. 1 is the structural principle schematic diagram of the present invention;

Fig. 2 is a schematic diagram of an embodiment of rotational speed torque measurement;

In the figure: 1-optical fiber, 2, 3-torsion bar, 4-spring, 5-long-period fiber grating or fused cone fiber, 6, 7-permanent magnet, 8-rotating body to be tested, 9-light source, 10-detection device.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

Example

A novel torque fiber optic sensor of the present invention includes a guide fiber 1, two torsion bars 2, 3, a long-period fiber grating or fused cone fiber 5, and a spring 4. The torsion bar 2 is connected to the torsion bar 3 through a spring 4, and the sensing optical fiber passes through the central axis of the two torsion bars and is respectively fixed at the ends of the two torsion bars. Among them, two torsion bars are connected by springs. The role played by the spring is not only the connection function, but also the reset function, that is, when there is no relative rotation between the two torsion bars, the spring can ensure that the two torsion bars are in the initial position. see picture 1. ,

In the embodiment shown in FIG. 2 , the light emitted by the light source 9 enters the optical fiber 1 , passes through the sensing optical fiber 5 , and is received by the optical detector 10 . A permanent magnet 6 is installed at the end of the torsion bar 3 , and a permanent magnet 7 with opposite polarity is also installed outside the tested rotating body 8 . When the rotating body 8 does not rotate, there is no relative displacement between the permanent magnets 6 and 7, so the position of the torsion bar 3 does not change. In this case, the sensing fiber 5 is not subjected to torque, so the transmission spectrum received by the detector 10 does not change;

When the object 8 rotates, it drives the magnet 7 at the same time, and generates a periodic attractive force on the magnet 6, thereby driving the torsion bar 3 to rotate periodically. The periodic rotation of the torsion bar 3 produces periodic torque changes, so that the sensing optical fiber 5 is subjected to periodic torque. This periodic torque action modulates the intensity or wavelength of light passing through the sensing fiber. The spectrum modulated by the torque variation can be received by the light detector 10 . The rotational speed can be measured by measuring the cycle of the change of the transmission spectrum of the sensing fiber 5 .

It can be seen from Figure 1 and Figure 2 that with this sensor structure, the optical path of the optical fiber is completely sealed, and has the characteristics of high sensitivity, anti-electromagnetic interference, corrosion resistance, explosion-proof and no interference with the measured site, and is more suitable for strong electromagnetic interference. , corrosive media and pollution and other harsh environments; in addition, compared with traditional torque sensors, using long-period fiber gratings or fused tapered optical fibers as measuring elements can achieve higher accuracy and range, and has a simple structure and low cost.

Claims (4)

1. a torque fiber optic sensor, comprising guide fiber (1), two torsion bars (2), (3), long-period fiber grating or fusion tapered fiber (5), spring (4), is characterized in that: all The two torsion bars (2), (3) are connected by a spring (4); the long-period optical fiber grating or fused tapered optical fiber (5) passes through the central axis of the two torsion bars (2), (3), and are respectively fixed at the ends of the two torsion bars (2), (3); the spring plays the role of connection and reset, and ensures that there is no relative displacement between the two torques (2), (3) without external force; when After the torque applied to the torsion bar is removed, the spring can ensure that the torsion bar returns to the initial position to realize repeated measurements. 2. A kind of torque optical fiber sensor as claimed in claim 1, it is characterized in that: the melting tapered optical fiber (5) in this sensor, is to form by single-mode optical fiber fusion tapering, and the diameter of its cladding and fiber core along the optical fiber The axial direction is gradually tapered. 3. A kind of optical fiber speed sensor based on this torque measurement principle as claimed in claim 1, is characterized in that: a magnet (6) is installed on a torsion bar (3), on the measured rotating mechanism (8) Another magnet (7) with opposite polarity is installed; the rotating mechanism (8) drives the torque sensor to output a signal every time it rotates one circle. 4. A kind of torque optical fiber sensor as claimed in claim 1, it is characterized in that: in this sensor structure, when torsion bar is subjected to the effect of force and rotates, sensing optical fiber is also subjected to the effect of torque and twists; Sensing optical fiber The light intensity or wavelength change of the transmission spectrum after twisting is related to the magnitude of the torque; the torque value can be obtained by measuring the light intensity or wavelength change of the transmission spectrum of the sensing fiber.

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