Sliding bearing oil film pressure-temperature double-parameter measuring device and method

Abstract

The invention provides a sliding bearing oil film pressure-temperature double-parameter measuring device and method, and the device comprises a driving device, a main shaft bearing assembly, a main shaft, a load, a pressure and temperature sensor, a demodulator, and an upper computer. The main shaft bearing assembly comprises a base, two rolling bearing seats, two rolling bearings, a sliding bearing seat and a sliding bearing; the pressure and temperature sensor is mounted on the sliding bearing; the demodulator is respectively in electric signal connection with the pressure and temperature sensor and the upper computer; and the upper computer is used for performing fitting operation according to the spectral data to obtain the cavity length of the FP cavity and the central wavelength of the FBG, and obtaining the oil film pressure corresponding to the cavity length and the oil film temperature corresponding to the central wavelength according to a preset rule. A pressure and temperature sensor is a sensor based on FP-FBG, and temperature-pressure cross influence is not formed, so that errors can be reduced, the anti-interference capability is high, and the durability and the stability are relatively good; the size is small, and the opening of the sliding bearing is small, so that the damage to the sliding bearing can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of sliding bearing oil film measurement, and in particular to a sliding bearing oil film pressure-temperature dual parameter measurement device and method. Background Art

[0002] Sliding bearings are widely used in power equipment such as aircraft engines, gas turbines, ship propulsion shaft systems, and large water pump units due to their stable, reliable, and noiseless operation. When sliding bearings operate under high speed and heavy load conditions, a high-pressure and high-temperature environment will be formed between the sliding bearing bushing and the mating surface of the rotating shaft. High pressure and high temperature may cause the lubricating oil film inside the sliding bearing to rupture, resulting in a boundary friction state or even a dry friction state between the rotating shaft and the bushing mating surface, accelerating the wear of the sliding bearing. Excessive wear of the sliding bearing may cause it to fail to work properly, and the worse result is damage to mechanical equipment and casualties.

[0003] Existing methods for measuring the oil film pressure of sliding bearings are mainly divided into indirect measurement method and direct measurement method. The indirect measurement method of oil film pressure mainly includes the oil film electrical parameter measurement method and the optical measurement method. The direct measurement method of oil film pressure mainly uses piezoelectric pressure sensors, strain gauge pressure sensors, thin film pressure sensors, etc. to measure the oil film pressure. Since the indirect measurement method of oil film pressure has to go through a series of theoretical calculations, and some parameters in the theoretical formula are time-varying, there will be a large error between the test results of the indirect measurement method and the actual situation; the direct measurement method of oil film pressure mainly uses electrical pressure sensors, which have defects such as susceptibility to interference, poor durability, and insufficient stability.

[0004] The existing methods for measuring the oil film temperature of sliding bearings are mainly divided into indirect measurement method and direct measurement method. The indirect measurement method of oil film temperature is mainly to indirectly evaluate the oil film temperature by measuring the temperature of the oil outlet of the sliding bearing lubricating oil; the direct measurement method is to drill a hole from the back of the bearing shell and introduce the temperature sensor into the oil film for measurement. Whether it is the direct method or the indirect method, the temperature sensors used are electrical temperature sensors such as thermocouples and thermal resistors, which also have problems such as poor environmental adaptability and susceptibility to interference.

[0005] At the same time, existing sensors used for measuring oil film temperature and pressure of sliding bearings have a common problem, that is, the sensors are large in size, requiring a large opening in the sliding bearing, which causes great damage to the sliding bearing. Summary of the invention

[0006] In view of this, the present invention proposes a sliding bearing oil film pressure-temperature dual-parameter measurement device and method to solve the technical problems proposed in the above background technology that the test results may have large errors compared with the actual situation, are susceptible to interference, have poor durability, insufficient stability, and cause great damage to the sliding bearing.

[0007] The technical solution of the present invention is achieved in this way: In a first aspect, the present invention provides a sliding bearing oil film pressure-temperature dual parameter measurement device, comprising a drive device, a main shaft bearing assembly, a main shaft, a load, a pressure and temperature sensor, a demodulator and a host computer, wherein: The main shaft load-bearing assembly comprises a base, two rolling bearing seats, two rolling bearings, a sliding bearing seat and a sliding bearing, the two rolling bearing seats are installed on the base at intervals, the rolling bearing is installed in the rolling bearing seat, the main shaft is installed in the two rolling bearings, the sliding bearing seat is installed on the base, the sliding bearing is installed in the sliding bearing seat, the main shaft passes through the sliding bearing, one end of the main shaft is connected to the driving device, and the other end is connected to the load; The pressure and temperature sensor is installed on the sliding bearing. The pressure and temperature sensor is a sensor based on FP and FBG, and is used to convert the collected oil film pressure and oil film temperature of the sliding bearing into an optical signal, and output it to a demodulator; The demodulator is respectively connected to the pressure and temperature sensor and the host computer by electrical signals, and is used to record the optical signal and convert it into spectral data for the host computer to retrieve; The host computer is used to retrieve the spectrum data of the demodulator, and perform fitting calculations based on the spectrum data to obtain the cavity length of the FP cavity and the central wavelength of the FBG, and obtain the oil film pressure corresponding to the cavity length and the oil film temperature corresponding to the central wavelength according to preset rules.

[0008] On the basis of the above technical scheme, preferably, the method of obtaining the pressure corresponding to the cavity length and the temperature corresponding to the center wavelength according to preset rules includes: obtaining the pressure value corresponding to the current cavity length and the temperature value corresponding to the center wavelength according to pre-stored pressure-cavity length experimental calibration data and temperature-center wavelength experimental calibration data, thereby realizing real-time measurement of the oil film pressure and oil film temperature of the sliding bearing.

[0009] On the basis of the above technical solution, preferably, the sliding bearing includes a radial bearing housing, an oil seal and a radial bushing, the radial bushing is installed in the radial bearing housing, the oil seal is respectively installed on the front and rear sides of the radial bearing housing, and the pressure temperature sensor is installed on the radial bushing.

[0010] On the basis of the above technical solution, preferably, a protection device is further included, the pressure and temperature sensor is installed in the protection device, a mounting hole is provided on the radial bush, and the protection device is installed in the mounting hole.

[0011] On the basis of the above technical solution, preferably, the protection device includes a protection tube, a protection cylinder and a hose, the protection tube is inserted into the protection cylinder, the hose is sleeved on the pressure and temperature sensor and inserted into the protection tube, the protection tube is inserted into the mounting hole and the protection cylinder is connected to the radial bushing.

[0012] On the basis of the above technical solution, preferably, a wire lead hole is provided on the radial housing of the bearing, and the wire lead hole is used for the jumper wire to pass through.

[0013] In a second aspect, the present invention provides a method for measuring the dual parameters of oil film pressure and temperature of a sliding bearing, using the dual parameter measuring device for oil film pressure and temperature of a sliding bearing described in the first aspect, comprising the following steps: Make multiple pressure and temperature sensors; Install the pressure and temperature sensor on the radial bush of the sliding bearing, and install the sliding bearing in the sliding bearing seat; The oil film pressure and oil film temperature of the sliding bearing are converted into optical signals through the pressure and temperature sensor, and output to the demodulator; The optical signal is recorded by a demodulator and converted into spectral data for access by a host computer; The upper computer performs fitting calculation based on the spectrum data of the demodulator to obtain the cavity length of the FP cavity and the central wavelength of the FBG, and obtains the oil film pressure corresponding to the cavity length and the oil film temperature corresponding to the central wavelength according to preset rules.

[0014] On the basis of the above technical scheme, preferably, the production of multiple pressure and temperature sensors includes: the pressure and temperature sensors are produced based on FBG single-mode optical fiber and multi-mode optical fiber microbubble type FP cavity; or, the pressure and temperature sensors are produced based on FBG single-mode optical fiber and hollow optical fiber type FP cavity; or, the pressure and temperature sensors are produced based on FBG single-mode optical fiber and multi-mode optical fiber solid type FP cavity.

[0015] On the basis of the above technical solution, preferably, the host computer performs fitting calculation according to the spectrum data of the demodulator to obtain the cavity length of the FP cavity, including: calculating the cavity length of the FP cavity according to the following formula: ; Where L is the cavity length of the FP cavity, λ 1 and λ 2 is the wavelength, and the phase difference is 2π.

[0016] On the basis of the above technical solution, preferably, the host computer performs fitting operation according to the spectrum data of the demodulator to obtain the central wavelength of the FBG, including: calculating the central wavelength of the FBG according to the following formula: ; In the formula, Δλ FBG is the center wavelength shift, ΔL is the FP cavity displacement, k P1 and k T1 are the sensitivities of the FP cavity displacement to pressure P and temperature T, respectively. P2 and k T2 are the sensitivities of the central wavelength shift of FBG with respect to pressure P and temperature T, respectively. ΔP and ΔT are the pressure and temperature changes of the environment in which the pressure and temperature sensor is located, respectively.

[0017] The sliding bearing oil film pressure-temperature dual parameter measuring device of the present invention has the following beneficial effects compared with the prior art: (1) The pressure and temperature sensor is a sensor based on FP-FBG. When the external pressure causes the diaphragm to deform, the pressure detection is achieved by demodulating the change in the FP cavity length, and the temperature detection is achieved by the change in the spectrum of FBG. The pressure measurement can be decoupled from the temperature, and the temperature can also be detected. The temperature will affect the zero drift and sensitivity change in the lower part at high temperature, so there will be no temperature-pressure cross-influence, which can reduce the error. It is insensitive to electromagnetic interference and can withstand extreme conditions, and has good stability. In addition, the pressure and temperature sensor based on FP-FBG is small in size, high in precision, and has a small opening in the sliding bearing, which can reduce damage to the sliding bearing. (2) Obtaining the pressure corresponding to the cavity length and the temperature corresponding to the center wavelength according to the preset rules includes: obtaining the pressure value corresponding to the current cavity length and the temperature value corresponding to the center wavelength according to the pre-stored pressure-cavity length experimental calibration data and the temperature-center wavelength experimental calibration data, thereby achieving real-time measurement of the oil film pressure and the oil film temperature of the sliding bearing. This method is relatively convenient and fast, and has good accuracy; (3) By providing a protective device, the pressure and temperature sensor is installed in the protective device, the radial bush is provided with a mounting hole, and the protective device is installed in the mounting hole. By protecting the pressure and temperature sensor through the protective device, the pressure and temperature sensor can withstand more extreme conditions, thereby further improving the stability of the device; (4) The manufacturing of multiple pressure and temperature sensors includes: the pressure and temperature sensors are manufactured based on FBG single-mode optical fiber and multi-mode optical fiber micro-bubble type FP cavity, mainly for low pressure measurement; or, the pressure and temperature sensors are manufactured based on FBG single-mode optical fiber and hollow optical fiber type FP cavity, mainly for high pressure measurement; or, the pressure and temperature sensors are manufactured based on FBG single-mode optical fiber and multi-mode optical fiber solid type FP cavity, mainly for ultra-high pressure measurement. Different pressure and temperature sensors can be manufactured for different pressure ranges, thereby increasing the measurement range and the application range of the device; (5) The host computer performs fitting calculations based on the spectrum data of the demodulator to obtain the cavity length of the FP cavity, including: based on the phase demodulation method, the wavelength is λ 1 ~λ 2 By scanning within the range, the cavity length of the FP cavity can be obtained according to the phase change of the interference fringes, that is, the cavity length of the FP cavity can be calculated according to the formula recorded in the text; (6) The host computer performs fitting operation on the spectrum data of the retrieved demodulator to obtain the central wavelength of the FBG, including: since the FP cavity displacement and the central wavelength offset of the FBG are linearly related to the pressure and temperature changes, a second-order mapping matrix is ​​established between the input and output of the pressure-temperature sensor to obtain the formula in the article. According to the formula, it can be seen that the pressure measurement can be decoupled from the temperature, and the temperature can also be detected, so that the central wavelength of the FBG can be calculated according to the formula. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 Schematic diagram of the structure of a sliding bearing oil film pressure-temperature dual parameter measurement device in an embodiment of the present invention; Figure 2 It is a schematic structural diagram of a pressure and temperature sensor based on a FBG single-mode optical fiber and a multi-mode optical fiber microbubble-type FP cavity in an embodiment of the present invention; Figure 3 It is a structural schematic diagram of a pressure and temperature sensor based on a FBG single-mode optical fiber and a hollow-core optical fiber type FP cavity in an embodiment of the present invention; Figure 4 It is a structural schematic diagram of a pressure and temperature sensor based on a FBG single-mode optical fiber and a multi-mode optical fiber solid type FP cavity in an embodiment of the present invention; Figure 5 is a schematic diagram of the structure of a protection device in an embodiment of the present invention; Figure 6 Schematic diagram of the structure of the radial pad in an embodiment of the present invention; Figure 7 It is a schematic diagram of the structure of installing a pressure and temperature sensor in a radial bush in an embodiment of the present invention; Figure 8 It is a cross-sectional view of a pressure and temperature sensor installed in a radial bush in an embodiment of the present invention; Fig. 9is a cross-sectional view of a sliding bearing in an embodiment of the present invention; Fig.10 is a schematic diagram of the structure of a demodulator in an embodiment of the present invention; Fig.11 Schematic diagram of the flow of the sliding bearing oil film pressure-temperature dual parameter measurement method in an embodiment of the present invention.

[0020] Description of reference numerals: 1-motor, 2-transmission mechanism, 3-first rolling bearing seat, 4-sliding bearing seat, 5-second rolling bearing seat, 6-spindle, 7-load, 8-base, 9-sliding bearing, 10-pressure and temperature sensor, 13-spectrometer, 14-host computer; 91-lead hole; 101- patch cord, 102- heat shrink tubing, 103- single-mode optical fiber, 104- FBG grating, 105- multi-mode optical fiber, 106- bubble; 111- patch cord, 112- heat shrink tube, 113- single-mode optical fiber, 114- FBG grating, 115- hollow core optical fiber, 116- single-mode optical fiber; 121- patch cord, 122- heat shrink tube, 123- single-mode optical fiber, 124- FBG grating, 125- air bubble, 126- multi-mode optical fiber; 11-protection device, 1101-protection tube, 1102-hose, 1103-protection cylinder, 1104-pressing plate, 1105-sealing ring; 12- radial tile, 1201- tile surface, 1202- tile block. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] It should be noted that the FP cavity, whose full name is Fabry-Pérot cavity, is a type of optical cavity composed of two parallel plane mirrors; the FBG, whose full name is Fiber Bragg Grating, is a diffraction grating formed by axially periodically modulating the refractive index of the optical fiber core by a certain method, and is a passive filtering device.

[0023] Reference Figure 1-10As shown, in the first aspect of the embodiment of the present invention, a sliding bearing oil film pressure-temperature dual parameter measurement device is proposed, including a drive device, a spindle 6 bearing assembly, a spindle 6, a load 7, a pressure and temperature sensor 10, a demodulator and a host computer 14, wherein: The main shaft bearing assembly includes a base 8, two rolling bearing seats, two rolling bearings, a sliding bearing seat 4 and a sliding bearing 9. The two rolling bearing seats (a first rolling bearing seat 3 and a second rolling bearing seat 5) are installed on the base 8 at intervals, the rolling bearings are installed in the rolling bearing seats, the main shaft 6 is installed in the two rolling bearings, the sliding bearing seat 4 is installed on the base 8, the sliding bearing 9 is installed in the sliding bearing seat 4, the main shaft 6 passes through the sliding bearing 9, one end of the main shaft 6 is connected to the driving device, and the other end is connected to the load 7; the sliding bearing 9 is provided with a first oil inlet hole and a first oil outlet hole, the sliding bearing seat 4 is provided with a second oil inlet hole connected to the first oil inlet hole and a second oil outlet hole connected to the first oil outlet hole, and the second oil inlet hole and the second oil outlet hole are connected by an oil pump to continuously provide oil pressure, reduce oil temperature, help form an oil film inside the sliding bearing 9, and prevent the main shaft 6 from performing dry friction with the bearing bush during high-speed rotation, resulting in a shortened service life of the sliding bearing 9; The driving device includes a motor 1 and a transmission mechanism 2. The transmission mechanism 2 is connected to the motor 1 and the main shaft 6 respectively. The motor 1 provides power to the transmission mechanism 2, thereby driving the main shaft 6 to rotate. The transmission mechanism 2 can be gear-driven. The pressure and temperature sensor 10 is installed on the sliding bearing 9. The pressure and temperature sensor 10 is a sensor based on FP and FBG, which is used to convert the collected oil film pressure and oil film temperature of the sliding bearing 9 into an optical signal and output it to the demodulator; the pressure and temperature sensor 10 can be evenly distributed and installed at different positions of the sliding bearing 9 to obtain the axial temperature distribution at different points; The demodulator is respectively connected to the pressure and temperature sensor 10 and the host computer 14 for electrical signal recording and converting the optical signal into spectral data for the host computer 14 to retrieve; The host computer 14 is used to retrieve the spectrum data of the demodulator, and perform fitting calculations based on the spectrum data to obtain the cavity length of the FP cavity and the central wavelength of the FBG, and obtain the oil film pressure corresponding to the cavity length and the oil film temperature corresponding to the central wavelength according to preset rules.

[0024] The sliding bearing oil film pressure-temperature dual parameter measurement device proposed in this embodiment uses a pressure-temperature sensor 10 as a sensor based on FP-FBG. When the external pressure causes the diaphragm to deform, pressure detection is achieved by demodulating the change in the FP cavity length, and temperature detection is achieved by changing the spectrum of FBG. The pressure measurement can be decoupled from the temperature, and the temperature can also be detected. The temperature will affect the lower part at high temperature and cause zero point drift and sensitivity change, so that temperature-pressure cross-influence will not be formed, thereby reducing errors. It is insensitive to electromagnetic interference and can withstand extreme conditions, and has good stability. In addition, the pressure-temperature sensor 10 based on FP-FBG is small in size and high in precision, and the opening in the sliding bearing 9 is small, which can reduce damage to the sliding bearing 9.

[0025] In some embodiments, the pressure corresponding to the cavity length and the temperature corresponding to the center wavelength obtained according to the preset rules include: obtaining the pressure value corresponding to the current cavity length and the temperature value corresponding to the center wavelength according to the pre-stored experimental calibration data of pressure-cavity length and the experimental calibration data of temperature-center wavelength, thereby achieving real-time measurement of the oil film pressure and the oil film temperature of the sliding bearing 9. The pressure corresponding to the cavity length and the temperature corresponding to the center wavelength obtained according to the preset rules include: according to the pre-stored experimental calibration data of pressure-cavity length and the experimental calibration data of temperature-center wavelength, the cavity length is substituted into the experimental calibration data of pressure-cavity length to obtain the pressure value corresponding to the current cavity length, and the center wavelength is substituted into the experimental calibration data of temperature-center wavelength to enrich the temperature value corresponding to the center wavelength, thereby achieving real-time measurement of the oil film pressure and the oil film temperature of the sliding bearing 9. This method is relatively convenient and fast, and has good accuracy.

[0026] In some embodiments, the sliding bearing 9 includes a radial bearing housing, an oil seal and a radial bushing 12, wherein the radial bushing 12 is installed in the radial bearing housing, the oil seal is installed at the front and rear sides of the radial bearing housing respectively, and the pressure and temperature sensor 10 is installed on the radial bushing 12. The radial bearing housing is composed of an upper half bushing and a lower half bushing, each of which is equipped with two thrust bushings, each of which is positioned axially and radially by a bushing groove, and the oil seals on both sides can also prevent the thrust bushing from slipping, and the upper half bushing and the lower half bushing are fitted together by a mortise and tenon joint, and are connected by connecting bolts and connecting nuts. The radial tile 12 and the tile surface 1201 are made of babbitt alloy material. Babbitt alloy is an alloy of metals such as tin, lead, antimony, and copper. It has tin or lead as the matrix and has the advantages of small friction coefficient, good anti-adhesion performance, strong oil adsorption, good corrosion resistance, etc. The tile block 1202 is made of steel and can withstand a large axial load. Eight mounting holes for installing sensors are drilled at the junction of the tile block 1202 and the tile surface 1201. The diameter and depth of the holes match the protective device 11 of the pressure and temperature sensor 10. Then the FP-FBG-based pressure and temperature sensor 10 is placed in to ensure that the microbubble FP cavity at the front end is not damaged. Then the sensor is tested to see if it can work normally.

[0027] In some embodiments, the sliding bearing oil film pressure-temperature dual parameter measurement device further includes a protection device 11, the pressure temperature sensor 10 is installed in the protection device 11, and a mounting hole is provided on the radial bush 12, and the protection device 11 is installed in the mounting hole. By protecting the pressure temperature sensor 10 through the protection device 11, the pressure temperature sensor 10 can withstand more extreme conditions, further improving the stability of the device.

[0028] In some embodiments, the protection device 11 includes a protection tube 1101, a protection cylinder 1103 and a hose 1102. The protection tube 1101 is inserted into the protection cylinder 1103. The hose 1102 is sleeved on the pressure and temperature sensor 10 and inserted into the protection tube 1101. The protection tube 1101 is inserted into the mounting hole and the protection cylinder 1103 is connected to the radial bush 12. The protection tube 1101 is a steel tube, and the hose 1102 is a soft yellow tube. The protection tube 1101 is inserted into the protection cylinder 1103. The pressure and temperature sensor 10 is sleeved with the hose 1102 and then inserted into the protection tube 1101. The pressure and temperature sensor 10 is fixed with glue. After the protection tube 1101 is inserted into the mounting hole, a pressing plate 1104 is used to press the outside of the protection cylinder 1103, and the pressing plate 1104 and the radial bush 12 are fastened by bolts. In actual design, in order to ensure the sealing of the mounting hole, a sealing ring 1105 is arranged between the end face of the protective tube 1103 and the radial bush 12. The sealing ring 1105 is sleeved on the protective tube 1101, thereby sealing between the protective tube 1103 and the radial bush 12, improving the sealing of the mounting hole, preventing oil leakage from the mounting hole, and improving reliability and stability.

[0029] In some embodiments, a lead-in hole 91 is provided on the radial housing of the bearing, and the lead-in hole 91 is used for the jumper wire to pass through. In order to facilitate the jumper wire to be led out from the sliding bearing 9, the lead-in hole 91 is provided on the upper side of the housing of the sliding bearing 9 and the sliding bearing seat 4, and then all the jumpers on the eight radial pads 12 around the sliding bearing 9 are marked at the ends of the jumpers in turn, and then all are tied with fine wires of high-temperature resistant materials, and are led out to the bearing seat through the lead-in hole 91, so as to facilitate the wire to be led out of the bearing seat more conveniently.

[0030] In some embodiments, the demodulator includes an optical coupler, a spectrometer 13 and a broadband light source. The pressure and temperature sensor 10 is connected to the optical coupler, and then the optical coupler is respectively connected to the spectrometer 13 and the broadband light source. The light emitted by the broadband light source enters the pressure and temperature sensors 10 (a), 10 (b), and 10 (c) respectively. The light is reflected by the end face of the optical fiber reflection end to produce an interference effect. The reflected light returns to the spectrometer 1315, and then the host computer 1416 collects the spectrum data of the scanning spectrometer 1315 in real time through the network interface, and performs real-time fitting calculation on the measured spectrum data to obtain the absolute length d of the FP cavity and the central wavelength of the FBG. Then, according to the experimental calibration data of the pressure-cavity length and the experimental calibration data of the temperature-central wavelength, the pressure value corresponding to the current cavity length and the temperature value corresponding to the central wavelength are obtained, thereby realizing real-time measurement of the pressure and temperature of the sliding bearing oil film.

[0031] In some embodiments, the pressure and temperature sensor 10 is made based on the FBG single-mode optical fiber and the multi-mode optical fiber micro-bubble type FP cavity, and specifically includes the following steps: S11: Take a single-mode optical fiber 103 with an appropriate length and a FBG grating 104, put it on a heat shrink tube 102, and peel off the coating layer; S12: Dip a piece of dust-free paper in alcohol and wipe the bare optical fiber that has been stripped of its coating clean; S13: Cut the optical fiber with a cutting knife to obtain a bare optical fiber end with a smooth end face and appropriate length; S14: The jumper 101 also performs the operations of steps S11 to S13 (without the heat shrink tube); S15: Use a fusion splicer to fusion-splice two bare optical fibers with smooth end surfaces, and use a heat shrink tube 102 to protect the fusion point; S16: Place the single-mode optical fiber close to the other end face of the FBG grating area and perform the operations of steps S11 to S13; S17: Prepare another multimode optical fiber 105 of appropriate length, perform steps S11-S13 (without heat shrink tubing), use a fusion splicer to fusion-splice two bare optical fibers with flat end faces, and protect the fusion point with a heat shrink tubing; S18: Use HF acid to corrode the end of the multimode optical fiber, and the multimode optical fiber end will appear concave. Place it on a fusion welding machine for discharge, and a bubble 106 (FP cavity) will form at the concave portion of the multimode optical fiber under the action of the current.

[0032] In some embodiments, the pressure and temperature sensor 10 is made based on FBG single-mode optical fiber and hollow-core optical fiber type FP cavity, and specifically includes the following steps: S101: Take a single-mode optical fiber 113 with an FBG grating 114 of appropriate length, put it on a heat shrink tube 112, and peel off the coating layer; S102: Dip a piece of dust-free paper in alcohol and wipe the bare optical fiber clean after the coating is stripped off. S103: Cut the optical fiber with a cutting knife to obtain a bare optical fiber end with a smooth end face and a suitable length; S104: The jumper 111 also performs the operations of steps S101 to S103 (without the heat shrink tube); S105: Use a fusion splicer to fusion-splice two bare optical fibers with smooth end surfaces, and use a heat shrink tube 112 to protect the fusion point; S106: Place the other end of the single-mode optical fiber 113 close to the end face of the FBG grating region 114 and perform the operations of steps S101 to S103 (without putting on the heat shrink tube); S107: prepare a hollow core optical fiber 115 of suitable length as the FP cavity, and perform the operations of steps S101 to S103 (without heat shrink tube); S108: Using a fusion splicer to fusion-splice two bare optical fibers with complete cross-sections; S109: using a cutting knife to cut off the excess hollow core optical fiber 115, ensuring that the remaining hollow core optical fiber length is 100-200 microns; S120: Prepare a single-mode optical fiber 116 of suitable length as a reflection surface, and perform steps 1-3 (without heat shrink tube). S121: Using a fusion splicer to fusion-splice the flat end faces of the hollow core optical fiber 115 and the single-mode optical fiber 116; S122: Use a cutting knife to cut off the remaining single-mode optical fiber 116 to ensure that the length of the remaining single-mode optical fiber is not less than 5 mm. At this time, both the left and right sides of the hollow-core optical fiber 115 are single-mode optical fibers, and an FP cavity can be formed.

[0033] In some embodiments, the pressure and temperature sensor 10 is made based on the FBG single-mode optical fiber and the multi-mode optical fiber solid FP cavity, and specifically includes the following steps: S201: Take a single-mode optical fiber 123 with an appropriate length and a FBG grating 124, put it on a heat shrink tube 122, and peel off the coating layer; S202: Dip dust-free paper in alcohol and wipe the bare optical fiber that has been stripped of its coating clean; S203: Cut the optical fiber with a cutting knife to obtain a bare optical fiber end with a flat end face and a suitable length; S204: The jumper 121 also performs the operations of steps S201 to S203 (without the heat shrink tube); S205: Using a fusion splicer to fusion-splice two bare optical fibers with smooth end surfaces, and protecting the fusion point with a heat shrink tube 122; S206: Place the other end of the single-mode optical fiber 123 close to the end face of the FBG grating region 124 and perform the operations of steps S201 to S203 (without putting on the heat shrink tube); S207: prepare a multimode optical fiber 126 of suitable length as the FP cavity, and perform the operations of steps S201 to S203 (without heat shrink tubing); S208: using HF acid to corrode the flat end of the multimode optical fiber 126, the multimode optical fiber end will be concave, and using a fusion splicer to fusion-splice the end face of the single-mode optical fiber close to the FBG grating area and the concave end face of the multimode optical fiber, the pit of the multimode optical fiber will form a small air bubble 125; S209: Use a cutting knife to cut off the redundant multimode optical fiber 126 to ensure that the remaining multimode optical fiber length is within 100-200 microns. At this time, a small air bubble 125 is formed on the left side of the multimode optical fiber.

[0034] It should be noted that: in the present invention, the dynamic detection device of the oil film pressure and temperature of the sliding bearing is used to provide the experimental environment required for measurement, to provide oil film support for studying the dynamic characteristics of the oil film pressure and temperature of the sliding bearing, and the number of mounting holes for installing sensors is not strictly limited, and can be increased or decreased according to the size of the actual radial pad 12 of the sliding bearing 9 and the need for pressure and temperature measurement. In theory, the more sensors, the better. In this example, each radial pad 12 is equipped with 8 FP-FBG-based pressure and temperature sensors 10, and 8 radial pads 12 are arranged around the sliding bearing 9, so the entire sliding bearing 9 is equipped with 64 FP-FBG pressure and temperature sensors 10; the measurement method does not strictly limit the number of bearing seats, and the specific number of settings is determined according to the number of sliding bearings 9 to be measured; at the same time, the present invention does not strictly limit the number of oil supply equipment, and the number of oil supply equipment can provide sufficient oil pressure, ensure timely cooling of oil temperature, and form a stable oil film.

[0035] A second aspect of the present invention provides a method for measuring the dual parameters of oil film pressure and temperature of a sliding bearing, using the dual parameter measuring device for oil film pressure and temperature of a sliding bearing described in the first aspect, such as Fig.11 As shown, the following steps are included: Step S1: manufacturing a plurality of pressure and temperature sensors 10; Step S2: installing the pressure and temperature sensor 10 on the radial pad 12 of the sliding bearing 9, and installing the sliding bearing 9 in the sliding bearing seat 4; Step S3: converting the oil film pressure and oil film temperature of the sliding bearing 9 into an optical signal through the pressure and temperature sensor 10, and outputting the optical signal to the demodulator; Step S4: recording the optical signal through a demodulator and converting it into spectrum data for the host computer 14 to retrieve; Step S5: The host computer 14 performs fitting calculation based on the spectrum data of the demodulator to obtain the cavity length of the FP cavity and the central wavelength of the FBG, and obtains the oil film pressure corresponding to the cavity length and the oil film temperature corresponding to the central wavelength according to preset rules.

[0036] In some embodiments, according to the principle of white light interference, when broadband light is incident into the optical fiber, the output spectrum of the sensor can be determined as: (1); Formula (1), a(λ) is the spectral profile of the background light source; b(λ) is the interference fringe contrast, λ and L are the scanning wavelength and length of the microbubble FP cavity respectively. In addition, is the phase of the interference spectrum, and its relationship with L can be expressed as (2); In formula (2), is the phase of the interference spectrum, and are the phases of the interference spectra of λ1 and λ2 respectively; Therefore, the phase demodulation method is adopted, and the wavelength is scanned within the range, and the cavity length of the FP cavity can be determined according to the phase change of the interference fringes; that is, the upper computer 14 performs fitting calculation according to the spectrum data of the demodulator to obtain the cavity length of the FP cavity, including: calculating the cavity length of the FP cavity according to the following formula: (3); In formula (3), L is the cavity length of the FP cavity, λ 1 and λ 2 is the wavelength, and the phase difference is 2π.

[0037] In some embodiments, when pressure and temperature act on the designed sensor, the cavity length of the FP cavity will change, so the FP cavity displacement can be expressed as: (4); In formula (4), ΔL is the displacement of the FP cavity, k P1 and k T1 are the sensitivities of the FP cavity displacement with respect to pressure P and temperature T, respectively, and ΔP and ΔT are the pressure and temperature changes of the environment in which the pressure-temperature sensor 10 is located, respectively; Since the center wavelength shift of FBG is linearly related to pressure and temperature changes, the relationship between the center wavelength shift and temperature and pressure changes can be expressed as: (5); In formula (5), Δλ FBG is the center wavelength shift, k P2 and k T2 are the sensitivities of the central wavelength shift of the FBG with respect to the pressure P and the temperature T, respectively, and ΔP and ΔT are the pressure and temperature changes of the environment in which the pressure and temperature sensor 10 is located, respectively; The host computer 14 performs fitting operation according to the spectrum data of the demodulator to obtain the central wavelength of the FBG, including: calculating the central wavelength of the FBG according to the following formula, that is, the second-order mapping matrix between the input and output of the pressure and temperature sensor 10 can be obtained according to formulas (4) and (5): (6); In formula (6), Δλ FBG is the center wavelength shift, ΔL is the FP cavity displacement, k P1 and k T1 are the sensitivities of the FP cavity displacement to pressure P and temperature T, respectively. P2 and k T2are the sensitivities of the central wavelength shift of the FBG with respect to pressure P and temperature T, respectively. ΔP and ΔT are the pressure and temperature changes of the environment in which the pressure-temperature sensor 10 is located, respectively.

[0038] It can be seen from formula (6) that pressure measurement can be decoupled from temperature, and temperature can also be detected. On the premise that the cavity length of the FP cavity is obtained according to formula (3), the central wavelength of the FBG can be calculated according to the above formulas (4) to (6).

[0039] In some embodiments, in step S1, the manufacturing of a plurality of pressure and temperature sensors 10 includes: the pressure and temperature sensors 10 are manufactured based on FBG single-mode optical fiber and multi-mode optical fiber micro-bubble type FP cavity, specifically including the following steps: S11: Take a single-mode optical fiber 103 with an appropriate length and a FBG grating 104, put it on a heat shrink tube 102, and peel off the coating layer; S12: Dip a piece of dust-free paper in alcohol and wipe the bare optical fiber that has been stripped of its coating clean; S13: Cut the optical fiber with a cutting knife to obtain a bare optical fiber end with a smooth end face and appropriate length; S14: The jumper 101 also performs the operations of steps S11 to S13 (without the heat shrink tube); S15: Use a fusion splicer to fusion-splice two bare optical fibers with smooth end surfaces, and use a heat shrink tube 102 to protect the fusion point; S16: Place the single-mode optical fiber close to the other end face of the FBG grating area and perform the operations of steps S11 to S13; S17: Prepare another multimode optical fiber 105 of appropriate length, perform steps S11-S13 (without heat shrink tubing), use a fusion splicer to fusion-splice two bare optical fibers with flat end faces, and protect the fusion point with a heat shrink tubing; S18: Use HF acid to corrode the end of the multimode optical fiber. The multimode optical fiber port will present a concave shape. Place it on a fusion welding machine for discharge. Under the action of the current, a bubble (FP cavity) will form at the concave portion of the multimode optical fiber. Put the multimode optical fiber into the liquid. Due to the influence of the static pressure of the liquid, the size of the bubble at the multimode optical fiber port will change. The signal is demodulated by the demodulator. S19: Place the entire pressure and temperature sensor 10 into the protection device 11.

[0040] The pressure and temperature sensor 10 based on the FBG single-mode optical fiber and the multi-mode optical fiber microbubble-type FP cavity obtained in this embodiment is mainly used for measuring low pressure.

[0041] In some embodiments, in step S1, the manufacturing of a plurality of pressure and temperature sensors 10 includes: the pressure and temperature sensors 10 are manufactured based on FBG single-mode optical fibers and hollow-core optical fiber-type FP cavities, specifically including the following steps: S101: Take a single-mode optical fiber 113 with an FBG grating 114 of appropriate length, put it on a heat shrink tube 112, and peel off the coating layer; S102: Dip a piece of dust-free paper in alcohol and wipe the bare optical fiber clean after the coating is stripped off. S103: Cut the optical fiber with a cutting knife to obtain a bare optical fiber end with a smooth end face and a suitable length; S104: The jumper 111 also performs the operations of steps S101 to S103 (without the heat shrink tube); S105: Use a fusion splicer to fusion-splice two bare optical fibers with smooth end surfaces, and use a heat shrink tube 112 to protect the fusion point; S106: Place the other end of the single-mode optical fiber 113 close to the end face of the FBG grating region 114 and perform the operations of steps S101 to S103 (without putting on the heat shrink tube); S107: prepare a hollow core optical fiber 115 of suitable length as the FP cavity, and perform the operations of steps S101 to S103 (without heat shrink tube); S108: Using a fusion splicer to fusion-splice two bare optical fibers with complete cross-sections; S109: using a cutting knife to cut off the excess hollow core optical fiber 115, ensuring that the remaining hollow core optical fiber length is 100-200 microns; S120: Prepare a single-mode optical fiber 116 of suitable length as a reflection surface, and perform steps 1-3 (without heat shrink tube). S121: Using a fusion splicer to fusion-splice the flat end faces of the hollow core optical fiber 115 and the single-mode optical fiber 116; S122: Use a cutting knife to cut off the remaining single-mode optical fiber 116, ensuring that the remaining single-mode optical fiber length is not less than 5 mm. At this time, both the left and right sides of the hollow-core optical fiber 115 are single-mode optical fibers, and an FP cavity can be formed. The hollow-core optical fiber is placed in a liquid. Due to the influence of the static pressure of the liquid, the size of the hollow-core optical fiber cavity will change, and a signal is demodulated by a demodulator; S123 : Place the entire pressure and temperature sensor 10 into the protection device 11 .

[0042] The pressure and temperature sensor 10 based on the FBG single-mode optical fiber and the hollow-core optical fiber type FP cavity obtained in this embodiment is mainly used for measuring high pressure.

[0043] In some embodiments, in step S1, the manufacturing of a plurality of pressure and temperature sensors 10 includes: the pressure and temperature sensors 10 are manufactured based on FBG single-mode optical fibers and multi-mode optical fibers solid FP cavities, specifically including the following steps: S201: Take a single-mode optical fiber 123 with an appropriate length and a FBG grating 124, put it on a heat shrink tube 122, and peel off the coating layer; S202: Dip dust-free paper in alcohol and wipe the bare optical fiber that has been stripped of its coating clean; S203: Cut the optical fiber with a cutting knife to obtain a bare optical fiber end with a flat end face and a suitable length; S204: The jumper 121 also performs the operations of steps S201 to S203 (without the heat shrink tube); S205: Using a fusion splicer to fusion-splice two bare optical fibers with smooth end surfaces, and protecting the fusion point with a heat shrink tube 122; S206: Place the other end of the single-mode optical fiber 123 close to the end face of the FBG grating region 124 and perform the operations of steps S201 to S203 (without putting on the heat shrink tube); S207: prepare a multimode optical fiber 126 of suitable length as the FP cavity, and perform the operations of steps S201 to S203 (without heat shrink tubing); S208: using HF acid to corrode the flat end of the multimode optical fiber 126, the multimode optical fiber end will be concave, and using a fusion splicer to fusion-splice the end face of the single-mode optical fiber close to the FBG grating area and the concave end face of the multimode optical fiber, the pit of the multimode optical fiber will form a small air bubble 125; S209: Use a cutting knife to cut off the redundant multimode optical fiber 126 to ensure that the remaining multimode optical fiber length is within 100-200 microns. At this time, the left side of the multimode optical fiber is a small air bubble 125, and the right side is air, so that an FP cavity can be formed. The multimode optical fiber is placed in the liquid. Due to the influence of the static pressure of the liquid, the size of the multimode optical fiber will change, and the signal is demodulated by the demodulator; S220 : placing the entire pressure and temperature sensor 10 into the protection device 11 .

[0044] The pressure and temperature sensor 10 based on the FBG single-mode optical fiber and the multi-mode optical fiber solid FP cavity obtained in this embodiment is mainly used for measuring ultra-high pressure.

[0045] The sliding bearing oil film pressure-temperature dual parameter measurement device and method proposed by the present invention have the following advantages: (1) Generally, pressure sensors are affected by temperature at high temperatures, resulting in zero-point drift and sensitivity changes, which results in temperature-pressure cross-effects and limits the practical application of the sensor. The present invention proposes a pressure-temperature sensor 10 based on FP-FBG. When the external pressure causes the diaphragm to deform, pressure detection is achieved by demodulating the change in the FP cavity length, and temperature detection is achieved by changing the spectrum of FBG. The pressure measurement can be decoupled from the temperature, and the temperature can also be detected. There will be no temperature-pressure cross-effect, thereby reducing the error. (2). A dual-parameter measurement method of oil film pressure and temperature of a sliding bearing is provided. The FP-FBG-based pressure and temperature sensor 10 is small in size and high in precision. It can reliably measure the distribution of oil film pressure without almost destroying the flow, boundary and pressure distribution of the oil film itself, thereby providing data support for the subsequent oil film force, oil film dynamic characteristics and nonlinearity; (3) The FP-FBG-based pressure and temperature sensor 10 is insensitive to electromagnetic interference and can withstand extreme conditions, including high temperature and high pressure as well as strong shock and vibration. It is easy to install and small in size. The opening in the sliding bearing 9 is small, which can reduce damage to the sliding bearing 9.

[0046] In summary, the present invention is economical and effective, and meets the urgent need for dynamic detection of oil film in sliding bearings. This method applies fiber grating sensors to oil film detection, has great originality and application value in the academic field, and is bound to have certain prospects in the future market.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A dual-parameter measurement device for oil film pressure and temperature of sliding bearings. It is characterized in that It includes a drive device, a main shaft bearing assembly, a main shaft, a load, a pressure and temperature sensor, a demodulator and a host computer, wherein: The main shaft load-bearing assembly comprises a base, two rolling bearing seats, two rolling bearings, a sliding bearing seat and a sliding bearing, the two rolling bearing seats are installed on the base at intervals, the rolling bearing is installed in the rolling bearing seat, the main shaft is installed in the two rolling bearings, the sliding bearing seat is installed on the base, the sliding bearing is installed in the sliding bearing seat, the main shaft passes through the sliding bearing, one end of the main shaft is connected to the driving device, and the other end is connected to the load; The pressure and temperature sensor is installed on the sliding bearing. The pressure and temperature sensor is a sensor based on FP and FBG, and is used to convert the collected oil film pressure and oil film temperature of the sliding bearing into an optical signal, and output it to a demodulator; The demodulator is respectively connected to the pressure and temperature sensor and the host computer by electrical signals, and is used to record the optical signal and convert it into spectral data for the host computer to retrieve; The host computer is used to retrieve the spectrum data of the demodulator, and perform fitting calculations based on the spectrum data to obtain the cavity length of the FP cavity and the central wavelength of the FBG, and obtain the oil film pressure corresponding to the cavity length and the oil film temperature corresponding to the central wavelength according to preset rules.

2. The sliding bearing oil film pressure-temperature dual parameter measuring device according to claim 1, It is characterized in that The method of obtaining the pressure corresponding to the cavity length and the temperature corresponding to the center wavelength according to preset rules includes: obtaining the pressure value corresponding to the current cavity length and the temperature value corresponding to the center wavelength according to pre-stored pressure-cavity length experimental calibration data and temperature-center wavelength experimental calibration data, thereby realizing real-time measurement of the oil film pressure and oil film temperature of the sliding bearing.

3. The sliding bearing oil film pressure-temperature dual parameter measuring device according to claim 1, It is characterized in that The sliding bearing comprises a radial bearing housing, an oil seal and a radial bushing. The radial bushing is installed in the radial bearing housing. The oil seal is installed on the front and rear sides of the radial bearing housing respectively. The pressure and temperature sensor is installed on the radial bushing.

4. The sliding bearing oil film pressure-temperature dual parameter measuring device according to claim 3, It is characterized in that It also includes a protection device, the pressure and temperature sensor is installed in the protection device, the radial bush is provided with a mounting hole, and the protection device is installed in the mounting hole.

5. The sliding bearing oil film pressure-temperature dual parameter measuring device according to claim 4, It is characterized in that The protection device includes a protection tube, a protection cylinder and a hose, wherein the protection tube is inserted into the protection cylinder, the hose is sleeved on the pressure and temperature sensor and inserted into the protection tube, the protection tube is inserted into the mounting hole and the protection cylinder is connected to the radial bushing.

6. The sliding bearing oil film pressure-temperature dual parameter measuring device according to claim 5, It is characterized in that The bearing radial housing is provided with a wire lead hole, and the wire lead hole is used for the jumper wire to pass through.

7. A method for measuring the dual parameters of oil film pressure and temperature of a sliding bearing, using the dual parameter measuring device for oil film pressure and temperature of a sliding bearing as claimed in any one of claims 1 to 6, It is characterized in that The following steps are involved: Make multiple pressure and temperature sensors; Install the pressure and temperature sensor on the radial bush of the sliding bearing, and install the sliding bearing in the sliding bearing seat; The oil film pressure and oil film temperature of the sliding bearing are converted into optical signals through the pressure and temperature sensor, and output to the demodulator; The optical signal is recorded by a demodulator and converted into spectral data for access by a host computer; The upper computer performs fitting calculation based on the spectrum data of the demodulator to obtain the cavity length of the FP cavity and the central wavelength of the FBG, and obtains the oil film pressure corresponding to the cavity length and the oil film temperature corresponding to the central wavelength according to preset rules.

8. The sliding bearing oil film pressure-temperature dual parameter measurement method according to claim 7, It is characterized in that The production of multiple pressure and temperature sensors includes: the pressure and temperature sensors are produced based on FBG single-mode optical fiber and multi-mode optical fiber microbubble type FP cavity; or, the pressure and temperature sensors are produced based on FBG single-mode optical fiber and hollow optical fiber type FP cavity; or, the pressure and temperature sensors are produced based on FBG single-mode optical fiber and multi-mode optical fiber solid type FP cavity.

9. The sliding bearing oil film pressure-temperature dual parameter measurement method according to claim 7, It is characterized in that The host computer performs fitting calculation according to the spectrum data of the demodulator to obtain the cavity length of the FP cavity, including: calculating the cavity length of the FP cavity according to the following formula: ； Where L is the cavity length of the FP cavity, λ 1 and λ 2 is the wavelength, and the phase difference is 2π.

10. The sliding bearing oil film pressure-temperature dual parameter measurement method according to claim 7, It is characterized in that The host computer performs fitting calculation according to the spectrum data of the demodulator to obtain the central wavelength of the FBG, including: calculating the central wavelength of the FBG according to the following formula: ； In the formula, Δλ FBG is the center wavelength shift, ΔL is the FP cavity displacement, k P1 and k T1 are the sensitivities of the FP cavity displacement to pressure P and temperature T, respectively. P2 and k T2 are the sensitivities of the central wavelength shift of FBG with respect to pressure P and temperature T, respectively. ΔP and ΔT are the pressure and temperature changes of the environment in which the pressure and temperature sensor is located, respectively.

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