CN116698406A - Single-mode fiber and detection device for bearing wear measurement - Google Patents

Abstract

The application discloses a single-mode fiber and a detection device for bearing abrasion measurement, wherein a first chirped fiber grating and a second chirped fiber grating are engraved at intervals inside the single-mode fiber, have the same parameters and are cascaded in the same chirp direction, the first/second chirped fiber grating end is a light source signal incident end, and the second/first chirped fiber grating end is a light source signal emergent end. The FP cavity formed by the chirped fiber gratings with the same parameters can generate finer and more interference fringes so as to realize high-precision measurement of the bearing abrasion loss according to the relation between the number of the interference fringes and the length of the grating region.

Description

Single-mode optical fiber and detection device for bearing wear measurement

technical field

The invention relates to the technical field of bearing wear measurement, in particular to a single-mode optical fiber and a detection device for bearing wear measurement.

Background technique

As an important part of the ship's power propulsion system, sliding bearings play a vital role. However, in use, wear and tear is extremely prone to occur. If it is not discovered in time, it will cause mechanical failure or even a major accident.

At present, the monitoring methods are mainly based on indirect measurement, including oil vibration and noise method, acoustic emission method, and strain method. Although the above methods can realize the measurement of wear amount in real time, the accuracy is low.

Therefore, how to provide a new wear measurement method to improve measurement accuracy is an urgent problem to be solved by those skilled in the art.

Contents of the invention

In view of this, the present invention provides a single-mode optical fiber and a detection device for bearing wear measurement, the main purpose of which is to realize high-precision measurement of bearing wear.

In order to achieve the above object, the present invention adopts the following technical solutions:

A single-mode optical fiber for bearing wear measurement, characterized in that the inner space is engraved with a first chirped fiber grating and a second chirped fiber grating, and the first chirped fiber grating and the second chirped optical fiber The gratings have the same parameters and are cascaded in the same chirp direction, the first chirped fiber grating end is the light source signal input end, and the second chirped fiber grating end is the light source signal output end; or the The second chirped fiber grating end is the light source signal incident end, and the first chirped fiber grating end is the light source signal output end _.

Preferably, the parameters include gate length, chirp coefficient and chirp direction.

Preferably, the other end of the first/second chirped fiber grating is also engraved with a fiber Bragg grating, so that the end of the fiber Bragg grating is always located on the side closer to the light source as the light source signal incident end.

A detection device for bearing wear measurement, characterized in that it includes a bearing wear detection sensor, a scanning laser and a signal demodulation system connected in sequence,

The bearing wear detection sensor includes a Sairon bolt and an armored shell, and the Sairon bolt is embedded with the above-mentioned single-mode optical fiber for bearing wear measurement; the armored shell is used to realize the Sairon Fixing of bolts and fiber optic jumpers;

The scanning laser is connected to the bearing wear detection sensor through the optical fiber jumper, and the scanning laser is a four-channel scanning laser, which is used to realize the simultaneous measurement of multiple wears of the bearing.

Preferably, the output light source of the scanning laser is broadband light with a resolution of 20pm.

Preferably, the parameters and intervals of the first chirped fiber grating and the second chirped fiber grating are determined according to the resolution of the laser scanner.

The detection device for bearing wear measurement according to claim 7, characterized in that, the scanning channel of the scanning laser is provided with a switch to realize single-channel measurement at different positions.

It can be seen from the above technical solutions that the present invention discloses a single-mode optical fiber and a detection device for bearing wear measurement. A chirped optical fiber grating is formed by writing a pair of chirped fiber gratings with the same parameters on the same single-mode optical fiber at the same time. -FP, and use the number of interference fringes of the chirped fiber grating-FP to perform high-precision demodulation of the wear amount of the sliding bearing. The present invention uses the linear relationship between the number of interference fringes of the chirped fiber grating-FP and the length of the gate area to complete the sliding bearing. Wear amount measurement, this technology is not easily affected by the environment, can realize early monitoring of bearing wear, and effectively improves the measurement accuracy of wear amount on the basis of existing technologies.

At the same time, the temperature sensitivity of the fiber Bragg grating is used to monitor the temperature of the measuring position of the sensor. The invention uses a chirped optical fiber grating-FP sensor to detect the wear state of the sliding bearing of the ship's power system in real time, completes the health monitoring of the bearing, and prevents major accidents caused by bearing failure.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the provided drawings without creative work.

Figure 1 is a schematic diagram of a single-mode fiber core;

Fig. 2 is the schematic diagram of detection device of the present invention;

Fig. 3 is a schematic diagram of a bearing wear detection sensor;

Figure 4 is the reflection spectrum of the sliding bearing wear detection sensor based on chirped fiber grating-FP;

Figure 5 is a schematic diagram of the variation of the reflection spectrum of the sliding bearing wear detection sensor, (a) is a schematic diagram of the variation of the reflection spectrum with temperature; (b) is a schematic diagram of the variation of the reflection spectrum with the amount of wear; (c) is a partial enlargement of the number of interference fringes in (b) picture.

In the figure: 1- bearing wear detection sensor; 2- four-channel scanning laser; 3- signal demodulation system; 4- armored shell; Fiber Bragg gratings written inside the core; 8, 9-chirped fiber gratings with the same parameters written.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Embodiment one

The embodiment of the present invention discloses a single-mode optical fiber used for bearing wear measurement, which mainly utilizes the sensitivity of the center wavelength of the fiber Bragg grating to temperature, and the number of interference fringes of the FP cavity of the chirped fiber Bragg grating P-cavity and the length of the grid area. The relationship realizes high-precision measurement of temperature and bearing wear.

Specifically as shown in Figure 1, the single-mode optical fiber used for bearing wear measurement in the present invention is engraved with a first chirped fiber grating 8 and a second chirped fiber grating 9 at an internal interval to form an FP cavity, so that signals of different wavelengths can travel along the chirped optical fiber The grating is reflected at different positions so that wavelengths are reflected and resonated to form F-P interference fringes.

Among them, the phase mask method can be used to record inside the single-mode optical fiber.

The first chirped fiber grating 8 and the second chirped fiber grating 9 have the same parameters. In order to ensure that the free spectral range of the interference fringes is consistent, they need to be cascaded in the same chirp direction, that is, the same positive chirp coefficient or the same anti-chirp coefficient, when in use, the 8th end of the first chirped fiber Bragg grating is the light source signal input end, the 9th end of the second chirped fiber Bragg grating is the light source signal output end; or the 9th end of the second chirped fiber Bragg grating is the light source signal input end, the first The 8 ends of a chirped fiber grating are the output ends of the light source signal.

Among them, the parameters of the first chirped fiber Bragg grating 8 and the second chirped fiber Bragg grating 9, including the gate length, interval, chirp coefficient, etc., can be selected and set according to the resolution of the scanning laser to clearly show the complete basic Stripes prevail. It should be noted that, in order to ensure the wear measurement range, the length or interval of the grid area cannot be reduced too much.

In one embodiment, the distance between the first chirped fiber grating and the second chirped fiber grating is 1mm, and the center wavelength of the two can be set to 1550nm, the chirp coefficient is 10nm/cm, and the gate length is 7mm. The free spectral range of the resulting FP cavity is 100pm.

In order to further optimize the above-mentioned technical solution, in the present invention, when the 8 ends of the first chirped fiber Bragg grating are the light source signal incident end, and the 9 ends of the second chirped fiber Bragg grating are the light source signal output end, the other end of the first chirped fiber Bragg grating 8 One end is engraved with a fiber Bragg grating 7, that is, the fiber Bragg grating 7 is always located on the side closer to the light source. In order to avoid the overlapping of the spectrum of the chirped fiber Bragg grating FP and the fiber Bragg grating, the central wavelength of the fiber Bragg grating should avoid this range. And in order to ensure that the fiber Bragg grating can measure the temperature of the worn location more accurately, it should be as close to the worn location as possible, and the length and interval of the grating area should be as small as possible.

In this embodiment, the distance between the fiber Bragg grating 7 and the first chirped fiber grating 8 is 1 mm, and the center wavelength thereof is set to 1520 nm, and the length of the grating region is 5 mm.

Embodiment two

In order to make it easier for those skilled in the art to understand the method of using the single-mode optical fiber of the present invention, the application further discloses a detection device for bearing wear measurement, as shown in Figure 2,

The device includes a bearing wear detection sensor, a scanning laser and a signal demodulation system connected in sequence. In one embodiment, the bearing wear detection sensor 1 is connected to the four-channel scanning laser 2 through an optical fiber jumper, and the signal demodulation system 3 is connected through a data line. Connect with the four-channel scanning laser 2, receive and process the output signal from the scanning laser 2.

The bearing wear detection sensor, as shown in Figure 3, includes a sairon bolt 5 and an armored casing 4, which are used to package and solidify the single-mode optical fiber 6, and structurally ensure that the optical fiber is isolated from temperature and stress changes during installation. At the same time, it is ensured that the encapsulation structure can wear out synchronously with the bearing.

Among them, the above-mentioned single-mode optical fiber used for bearing wear measurement is embedded inside the Sairon bolt; specifically, the fiber Bragg grating 7 is used as the incident end, and the chirped fiber grating 9 is inserted into the Sairon bolt 5 in the direction of the exit end. , and glued with 353ND fiber optic glue. When bonding, the device needs to be placed on a heating platform at 80°C for 24 hours. Finally, the cured optical fiber is put into the armored casing 4 to complete the manufacture of the bearing wear detection sensor 1 .

In one embodiment, the Sailong bolt is made of Sailong material, and the inside is tapped into a through hole for placing optical fibers; preferably, the size of the Sailong bolt is set as follows: the external thread is M20, and the thread length is 30mm, so that It is connected with the armored shell, and the internal through hole of the bolt is M3.5.

The armored shell has the functions of tensile resistance, compression resistance and bending resistance, and is used to realize the fixing of the Sairon bolt and the optical fiber jumper and protect the internal optical fiber.

The end of the bearing wear detection sensor of the invention wears synchronously with the sliding bearing, and is used for simultaneously detecting the wear amount and temperature of the sliding bearing.

The scanning laser in this application is a four-channel scanning laser, which is used to realize the simultaneous measurement of multiple bearing wears; at the same time, the scanning channels of the scanning laser are provided with switches to realize single-channel measurement at different positions.

In one embodiment, the output light source of the scanning laser is broadband light with a resolution of 20pm.

Further, the signal demodulation system 3 demodulates the spectrum collected from the four-channel scanning laser, obtains the number of interference fringes of the chirped fiber grating-FP cavity and the center wavelength offset of the fiber Bragg grating, and realizes the temperature and center High-precision demodulation of wavelengths.

In one embodiment, the signal demodulation system 3 is completed by the Labview program on the PC, which demodulates the spectrum collected from the four-channel scanning laser 2, obtains the wear amount and temperature parameters, and sets the early warning value at the same time, reminding in time to replace the slide bearings.

Among them, the original reflection spectrum curve of the sensor is shown in Fig. 4 . The demodulation of the bearing wear detection sensor is shown in Figure 5. According to the offset of the center wavelength of the fiber Bragg grating in Figure 5(a), the temperature during wear can be known, so when calculating the number of interference fringes in Figure 5(b), The temperature can be regarded as known. According to Figure 5(b), the number of interference fringes at each wear moment can be obtained. Figure 5(c) is a partial enlarged view of the number of interference fringes in Figure 5(b). According to the number of interference fringes and the The linear relationship of the length calculates the amount of wear of the bearing.

The chirped fiber grating-FP formed by the present invention has extremely fine interference fringes. At a resolution of 20pm, there are 9 interference fringes per nm in the spectral range, and the accuracy can reach 0.03mm in the effective spectral width range of 20nm. There is a linear relationship between the number of stripes and the length of the chirped fiber grating. As the sensor wears out, the length of the gate region decreases, and the number of interference fringes also decreases. As shown in Figure 5(b), when the length of the gate region is 4mm, the number of corresponding fringes is the least. The linear relationship can be demodulated by using the interference fringe counting method.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other. As for the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and for relevant details, please refer to the description of the method part.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (7)

1. A single-mode optical fiber for bearing wear measurement, characterized in that, the inner space is engraved with a first chirped fiber grating and a second chirped fiber grating, the first chirped fiber grating and the second chirped fiber grating Chirped fiber gratings have the same parameters and are cascaded in the same chirp direction, the first chirped fiber grating end is the light source signal input end, and the second chirped fiber grating end is the light source signal output end; or The second chirped fiber grating end is the light source signal incident end, and the first chirped fiber grating end is the light source signal output end. 2. A single-mode optical fiber for bearing wear measurement according to claim 1, wherein the parameters include gate length, chirp coefficient and chirp direction. 3. A kind of single-mode optical fiber for bearing wear measurement according to claim 1, characterized in that, the other end of the first/second chirped fiber grating is also engraved with a fiber Bragg grating, and the fiber Bragg grating Located on the side closer to the light source. 4. A detection device for bearing wear measurement, characterized in that it comprises a bearing wear detection sensor, a scanning laser and a signal demodulation system connected in sequence, The bearing wear detection sensor comprises a Sairon bolt and an armored shell, and the Sairon bolt is internally embedded with the single-mode optical fiber for bearing wear measurement described in any one of claims 1-3; the armored shell is used for To realize the fixation of the Sairon bolt and the optical fiber; The scanning laser is connected to the bearing wear detection sensor through the optical fiber jumper, and the scanning laser is a four-channel scanning laser, which is used to realize the simultaneous measurement of multiple wears of the bearing. 5 . The detection device for bearing wear measurement according to claim 4 , wherein the output light source of the scanning laser is broadband light with a resolution of 20 pm. 6. A kind of detection device for bearing wear measurement according to claim 4, is characterized in that, according to the resolution of described laser scanner, determine the parameter sum of the first chirped fiber grating and the second chirped fiber grating interval. 7. A detection device for bearing wear measurement according to claim 4, characterized in that, the scanning channel of the scanning laser is provided with a switch to realize single-channel measurement at different positions.