1. An optical fiber sensor for monitoring oil vibration is characterized by mainly comprising a cylindrical shell, an end cover, a pressure body, a damping cone, a balance spring, an O-shaped sealing ring, a sensing optical fiber and a reference optical fiber; the cylindrical shell is internally provided with a through hole, and one end of the cylindrical shell is provided with an extension edge which is convenient to be connected with the end cover by a screw; the other end of the cylindrical shell is provided with an M20 multiplied by 1.5 external thread which is convenient to be connected with a standard sensor interface of an oil liquid channel in equipment; the end cover is provided with an O-shaped sealing ring groove for installing an O-shaped sealing ring to seal oil in the cylindrical shell; the compression body is a cylinder with an I-shaped section, the outer wall of the compression body is a cylindrical thin wall, and the thin wall is in clearance fit with the through hole of the cylindrical shell; a damping cone is arranged on one surface of the middle part of the end cover facing the cylindrical shell, and the maximum diameter of the damping cone is consistent with the inner diameter of the damping pipe; through holes of the sensing optical fiber and the reference optical fiber are symmetrically arranged on two sides of the middle part of the end cover; the balance spring is arranged between the thin wall of the pressure body and the end cover; the sensing fiber and the reference fiber are respectively provided with the same FBG (fiber Bragg Grating) grating which is respectively arranged in the through holes of the end cover corresponding to the compression surface.

2. The optical fiber sensor for oil vibration monitoring as claimed in claim 1, wherein a circular pressure receiving surface is arranged in the middle of the pressure receiving body; the middle part of the pressure surface is provided with damping tubes with equal length symmetrically, and the damping tubes are matched with a damping cone arranged on an end cover on the same central axis; and through holes corresponding to the sensing optical fiber and the reference optical fiber through holes of the end cover are formed in the two sides of the middle of the compression surface.

3. The optical fiber sensor for oil vibration monitoring of claim 1, wherein the balancing springs are uniformly distributed in 2 (low pressure 2MPa), 4 (medium pressure below 10 MPa) or 6 (high pressure above 10 MPa) according to the pressure of oil in the device.

4. A fiber optic sensor for oil vibration monitoring according to claim 1, wherein the through holes in the end caps housing the sensing and reference fibers are sealed; the through hole for installing the sensing optical fiber on the compression surface is sealed, and the through hole for installing the reference optical fiber on the compression surface is not sealed and is set as a free end.

Background

The oil acts as a lubrication, heat exchange and cleaning system in the mechanical equipment, called "blood" of the equipment. In particular, in a hydraulic system using oil to transmit power, the operation state of the oil (such as changes in parameters such as vibration and pressure) greatly affects the safe operation of the equipment and the accuracy and stability of the movement of the actuator.

The oil inevitably presents a vibration state due to the operation of mechanical equipment, the change of the flow velocity of the oil, sudden pressure change and the like. In addition, no matter the particle pollutants invaded from the outside of the equipment or generated inside the equipment are closely related to the vibration state of the oil from the source and the frequency of the particle pollutants generated by the equipment, particularly, the particle pollutants have a shearing effect on the inner surfaces of elements or friction pairs along with the vibration of the oil, namely, the existence of the particle pollutants can influence the dynamic characteristics of the oil and can be reflected in the vibration signal of the oil to different degrees, and the vibration parameters of the oil can be obtained by measurement more directly, quickly and accurately than other state parameters of the equipment. Therefore, the method has important scientific significance for monitoring the vibration state of the oil liquid, effectively evaluating the health state of the equipment and realizing safe and reliable operation of the equipment.

Common vibration monitoring is an important link for performing work such as equipment state monitoring, fault diagnosis, dynamic performance test and optimization design of products and the like, and is widely applied in different fields, for example, the invention (CN110567571A) discloses an oil pipeline vibration detection method based on optical fiber distributed monitoring, which comprises the following steps: the optical fiber vibration monitoring host simulates a pipeline noise spectrum under a normal condition and simulates friction vibration noise characteristics of an oil pipeline under a vibration condition, acquires vibration signals generated by friction of the oil pipeline in real time and transmits the vibration signals to the optical fiber vibration monitoring host, the optical fiber vibration monitoring host carries out preprocessing and mode recognition algorithm processing according to the vibration signal characteristics, compares the processing result with the simulation result, confirms the friction vibration condition of the oil pipeline, and gives an alarm when the vibration amplitude exceeds a safety range. The invention can accurately analyze the vibration condition of the oil delivery pipe. The invention (CN111692054A) discloses a wind power gear box flaw detection system based on vibration time domain and frequency domain signal intelligent analysis, which comprises: the device comprises an oil liquid analysis device, a vibration monitoring device, a signal conversion device and a fault analysis device; the oil liquid analysis device is used for analyzing oil liquid of the wind turbine gearbox and sending an oil liquid analysis result to the fault analysis device according to a detection signal sent by the fault analysis device; therefore, the vibration monitoring device is also used for monitoring the vibration condition of the gearbox of the wind turbine generator, and the oil liquid is not analyzed by the vibration device.

With the development of optical fiber technology, the optical fiber sensor technology using optical fiber as a conducting medium is gradually applied to oil detection instruments, and is highly anti-interference and not influenced by temperature, electromagnetism and the like, documents (optical fiber oil contamination monitoring sensor design, invar and brave, vicious, shaggy, shaohan, instrument technology and sensor, 2006.11) design an optical fiber sensor probe based on the Beer-Lambert law by using the absorption and scattering effects of contamination particles suspended in oil on incident light, and reflect the change situation of oil contamination degree according to the change of luminous intensity. The invention (CN111997600A) relates to a distributed optical fiber acoustic vibration (DAS) based simulation experiment device and a method for monitoring the flow velocity and the flow state of a shaft fluid. The DAS module consists of a laser light source (18), a vibration sensing optical fiber (17), a vibration signal acquisition processor (19) and a high-speed camera (20), and aims to synchronously acquire images and vibration signals and measure fluid vibration signals by using an optical time domain principle and a backward Rayleigh scattering principle. Therefore, the technical schemes can realize the monitoring of the particulate matters in the oil or the motion state of the oil, but a plurality of complex algorithms and monitoring devices are involved, so that the real-time performance and the monitoring effect are further improved.

Disclosure of Invention

In order to monitor oil vibration signals in equipment by using an optical fiber technology and overcome the defects of the technical scheme, the invention provides the optical fiber sensor for oil vibration monitoring, which is used for extracting the vibration signal characteristics of oil and further monitoring the content of particle pollutants which are essentially connected with the oil, thereby representing the reliability of equipment operation, fusing and intersecting monitoring technologies of oil monitoring and vibration monitoring which belong to different disciplines and achieving the purpose of safe operation of the equipment.

The technical problem to be solved by the invention is how to efficiently realize the monitoring of the oil vibration in the equipment and obtain the vibration signal of the oil so as to achieve the aim of safe operation of the equipment.

In order to solve the technical problems, the invention provides the following technical scheme:

an optical fiber sensor for monitoring oil vibration is characterized by mainly comprising a cylindrical shell, an end cover, a pressure body, a damping cone, a balance spring, an O-shaped sealing ring, a sensing optical fiber and a reference optical fiber; the cylindrical shell is internally provided with a through hole, and one end of the cylindrical shell is provided with an extension edge which is convenient to be connected with the end cover by a screw; the other end of the cylindrical shell is provided with an M20 multiplied by 1.5 external thread which is convenient to be connected with a standard sensor interface of an oil liquid channel in equipment; the end cover is provided with an O-shaped sealing ring groove for installing an O-shaped sealing ring to seal oil in the cylindrical shell; a damping cone is arranged on one surface of the middle part of the end cover facing the cylindrical shell, and the maximum diameter of the damping cone is consistent with the inner diameter of the damping pipe; through holes of the sensing optical fiber and the reference optical fiber are symmetrically arranged on two sides of the middle part of the end cover; the compression body is a cylinder with an I-shaped section, the outer wall of the compression body is a cylindrical thin wall, and the thin wall is in clearance fit with the through hole of the cylindrical shell; a circular pressure-receiving surface is arranged in the middle of the pressure-receiving body; the middle part of the pressure surface is provided with damping tubes with equal length symmetrically, and the damping tubes are matched with a damping cone arranged on an end cover on the same central axis; through holes corresponding to the sensing optical fiber and the reference optical fiber through holes of the end cover are formed in the two sides of the middle of the compression surface; the balance springs are arranged between the thin wall of the pressure-bearing body and the end cover, and can be uniformly distributed for 2 (low pressure 2MPa), 4 (medium pressure below 10 MPa) or 6 (high pressure above 10 MPa) according to the pressure of oil liquid in the equipment; the sensing optical fiber and the reference optical fiber are respectively provided with the same FBG (fiber Bragg Grating) grating, are respectively arranged in the through holes of the end cover corresponding to the pressure surface and seal the through holes in the end cover provided with the sensing optical fiber and the reference optical fiber; the through hole for installing the sensing optical fiber on the compression surface is sealed, and the through hole for installing the reference optical fiber on the compression surface is not sealed and is set as a free end.

The following explains in detail how to efficiently monitor the vibration of the oil in the equipment to obtain the vibration signal of the oil so as to achieve the purpose of safe operation of the equipment; the optical fiber sensor for monitoring the oil vibration adopts the following technical scheme:

(1) the arrangement of the pressure body can realize the longitudinal unicity of the vibration direction of the sensing optical fiber under the oil

Because of the operation of mechanical equipment, the change of the flow velocity of oil, sudden change of pressure and other reasons, the oil inevitably presents a vibration state, and the existence of particle pollutants in the oil can influence the vibration signal of the oil. However, the vibration signal of the oil is basically longitudinal vibration in the oil pipe, and the amplitude of the transverse vibration is smaller than that of the longitudinal vibration, but the transverse vibration still generates transverse vibration interference on the sensing optical fiber in the oil without processing, so that the amplitude of the telescopic displacement generated in the longitudinal direction is influenced.

The technical scheme for solving the technical problem is that the compression body is a cylinder with an I-shaped section, the outer wall of the compression body is a cylindrical thin wall, and the thin wall is in clearance fit with the through hole of the cylindrical shell; because the longitudinal vibration amplitude of the oil is far greater than the transverse vibration amplitude of the oil, the pressed body can only move along the axial direction of the through hole of the cylindrical shell under the action of the longitudinal vibration pressure of the oil, the transverse vibration amplitude is small and limited by the gap between the thin wall and the through hole of the cylindrical shell, the force generated by the transverse vibration is balanced on the circumference of the pressed body, and the transverse displacement of the pressed body can be ignored.

In addition, a circular pressure-bearing surface is arranged in the middle of the pressure-bearing body; the middle part of the pressure surface is provided with damping tubes with equal length symmetrically, and the damping tubes are matched with a damping cone arranged on an end cover on the same central axis; and through holes corresponding to the sensing optical fiber and the reference optical fiber through holes of the end cover are formed in the two sides of the middle of the compression surface. According to the theory of the long and thin hole flow, the damping tube increases the oil pressure difference on two sides of the pressure receiving surface, the acting force of the longitudinal vibration of the oil on the pressure receiving body is further increased in quantity, the advantage of the longitudinal vibration of the pressure receiving body is improved, and the longitudinal stress singleness of the sensing optical fiber is guaranteed. And because the maximum diameter of the damping cone is consistent with the inner diameter of the damping pipe, the matching position of the damping pipe and the damping cone arranged on the pressure-bearing body is changed simultaneously according to the change of the longitudinal vibration pressure of the oil liquid, so that the motion damping generated by the pressure-bearing body is correspondingly changed. If the pressed body moves towards the end cover longitudinally under the longitudinal vibration of the oil, the clearance between the damping pipe and the damping cone is smaller and smaller, the damping is increased, and finally the movement of the pressed body is stopped; on the contrary, when the pressed body is far away from the end cover to move longitudinally under the action of the oil longitudinal vibration pressure, the gap between the damping pipe and the damping cone is larger and larger, the damping is reduced, the oil hydraulic pressure difference on two sides of the pressed surface is reduced, and the movement of the pressed body is gradually stopped under the action of the balance spring.

(2) The reference optical fiber is arranged to eliminate the interference of the vibration of the equipment body on the oil vibration signal and the influence of the temperature on the sensing optical fiber

The sensing optical fiber and the reference optical fiber are respectively provided with the same FBG (fiber Bragg grating) gratings which are respectively arranged in through holes corresponding to the pressed surfaces of the end covers, and the through holes in the end covers provided with the sensing optical fiber and the reference optical fiber are sealed; in order to eliminate the interference of the vibration of the equipment body on the sensing optical fiber to the oil vibration signal, the through hole for mounting the sensing optical fiber on the pressed surface is sealed, and the through hole for mounting the reference optical fiber on the pressed surface is not sealed and is arranged as a free end. The pressure-bearing body moves towards the end cover or away from the end cover under the action of the longitudinal vibration pressure of the oil, and the sensing optical fiber is sealed at the pressure-bearing surface and the two ends of the end cover and can generate longitudinal displacement along with the vibration of the oil pressure; and only one end of the reference optical fiber on the end cover is sealed, and one end of the reference optical fiber on the pressure surface is free, so that the reference optical fiber cannot generate longitudinal displacement along with vibration of oil hydraulic pressure. However, under the influence of the vibration generated by the device body, some non-oil vibration interference signals may be generated, and these interference signals simultaneously affect the sensing optical fiber and the reference optical fiber in equal quantity, so that the interference and the temperature influence can be eliminated by performing subtraction in the demodulator of the optical fiber signals.

(3) The arrangement of the balance spring can realize the monitoring of the reciprocating motion of the sensing optical fiber on the longitudinal vibration of the oil

Because the longitudinal vibration of the oil is a reciprocating process, when the pressed body moves longitudinally towards the end cover under the longitudinal vibration of the oil, the gap between the damping pipe and the damping cone is smaller and smaller, the damping is increased, the balance spring is pressed, and finally the movement of the pressed body is stopped; on the contrary, when the pressed body is far away from the end cover to move longitudinally under the action of the oil longitudinal vibration pressure, the gap between the damping pipe and the damping cone is larger and larger, the damping is reduced, the oil hydraulic pressure difference on two sides of the pressed surface is reduced, and therefore the movement of the pressed body is gradually stopped under the action of the balance spring. Therefore, the springs are arranged between the thin wall of the pressure-bearing body and the end cover, and can be uniformly distributed for 2 (low pressure 2MPa), 4 (medium pressure below 10 MPa) or 6 (high pressure above 10 MPa) according to the pressure of oil in the equipment, so that the monitoring of the reciprocating motion of the longitudinal vibration of the oil by the sensing optical fiber is realized.

(4) The arrangement of the O-shaped sealing ring and the thread can realize the structural assembly and connection of the invention

One end of the cylindrical shell is provided with an extension edge which is convenient to be connected with the end cover through screws; the other end of the cylindrical shell is provided with an M20 multiplied by 1.5 external thread which is convenient to be connected with a standard sensor interface of an oil liquid channel in equipment;

the end cover is provided with an O-shaped sealing ring groove for installing an O-shaped sealing ring to seal oil in the cylindrical shell; meanwhile, before the cylindrical shell is connected, the installation and arrangement of components such as the sensing optical fiber, the reference optical fiber and the like on the compression body are facilitated.

In conclusion, the beneficial effects of the invention are as follows:

(1) the pressure body is a cylinder with an I-shaped section, the outer wall of the pressure body is a cylindrical thin wall, and the thin wall is in clearance fit with the through hole of the cylindrical shell; a circular pressure-receiving surface is arranged in the middle of the pressure-receiving body; the middle part of the pressure surface is provided with damping tubes with equal length symmetrically, and the damping tubes are matched with a damping cone arranged on an end cover on the same central axis; through holes corresponding to the sensing optical fiber and the reference optical fiber through holes of the end cover are formed in the two sides of the middle of the compression surface, and the maximum diameter of the damping cone is consistent with the inner diameter of the damping pipe. The damping tube increases the oil pressure difference on two sides of the pressed surface, and the pressed body can only move along the axial direction of the through hole of the cylindrical shell under the action of the longitudinal vibration pressure of the oil, so that the singleness of the longitudinal vibration stress of the sensing optical fiber is guaranteed.

(2) The through hole for installing the reference optical fiber on the compression surface is not sealed and is arranged as a free end, and the influence of vibration generated by the equipment body can be eliminated by deducting in the demodulation instrument of the optical fiber signal.

(3) The arrangement of the balance spring can realize the monitoring of the reciprocating motion of the longitudinal vibration of the oil liquid by the sensing optical fiber.

(4) The other end of the cylindrical shell is provided with M20 multiplied by 1.5 external threads, so that the cylindrical shell is conveniently connected with a standard sensor interface of an oil liquid channel in equipment.

(5) The end cover is provided with an O-shaped sealing ring groove for installing an O-shaped sealing ring to seal oil in the cylindrical shell; meanwhile, before the cylindrical shell is connected, the installation and arrangement of components such as the sensing optical fiber, the reference optical fiber and the like on the compression body are facilitated. The invention has simple structure, is convenient to install and debug, and can accurately realize the monitoring of oil vibration.

Drawings

FIG. 1 is a schematic structural diagram of the present invention.

Fig. 2 is a view showing the position of the pressure body of the present invention away from the end cap.

Fig. 3 is a view showing the position of the pressure body of the present invention toward the end cap.

FIG. 4 is a schematic diagram of an embodiment of the present invention.

In the figure, 1 is an external thread of a cylindrical shell, 2 is a cylindrical shell, 3 is an extension edge of the cylindrical shell, 4 is a compression body, 5 is a compression surface, 6 is a damping tube, 7 is a balance spring, 8 is a sensing optical fiber, 9 is a reference optical fiber, 10 is a damping cone, 11 is an end cover, 12 is an O-shaped sealing ring, 13 is an ASE light source, 14 is a 3db coupler, 15 is a 1# circulator, 16 is a 2# circulator, 17 is an optical fiber demodulator, 18 is a computer, and 19 is an oil channel to be monitored.

Detailed Description

The present invention will be described in further detail with reference to the following drawings and examples.

As shown in fig. 1, the invention provides an optical fiber sensor for monitoring oil vibration, which mainly comprises a cylindrical shell 2, an end cover 11, a pressure body 4, a damping cone 10, a balance spring 7, an O-shaped sealing ring 12, a sensing optical fiber 8 and a reference optical fiber 9; a through hole is arranged in the cylindrical shell 2, and an extension edge 3 is arranged at one end of the cylindrical shell, so that the cylindrical shell is conveniently connected with an end cover through a screw; the other end of the cylindrical shell 2 is provided with an M20 multiplied by 1.5 external thread 1 which is convenient to be connected with a standard sensor interface of an oil liquid channel in equipment; the end cover 11 is provided with an O-shaped sealing ring groove for installing an O-shaped sealing ring 12 to seal oil in the cylindrical shell 2; a damping cone 10 is arranged on one surface of the middle part of the end cover 11 facing the cylindrical shell, and the maximum diameter of the damping cone 10 is consistent with the inner diameter of the damping tube 6; through holes of the sensing optical fiber 8 and the reference optical fiber 9 are symmetrically arranged on two sides of the middle part of the end cover 11; the pressed body 4 is a cylinder with an I-shaped section, the outer wall of the pressed body is a cylindrical thin wall, and the thin wall is in clearance fit with the through hole of the cylindrical shell 2; a circular pressure-receiving surface 5 is arranged in the middle of the pressure-receiving body 4; the middle part of the pressure surface 5 is provided with damping tubes 6 with equal length symmetrically, and the damping tubes 6 are matched with a damping cone 10 arranged on an end cover on the same central axis; through holes corresponding to the through holes of the sensing optical fiber 8 and the reference optical fiber 9 of the end cover are formed in the two sides of the middle of the compression surface 5; the balance springs 7 are arranged between the thin wall of the pressure-bearing body 4 and the end cover 11, and can be uniformly distributed in 2 (low pressure 2MPa), 4 (medium pressure below 10 MPa) or 6 (high pressure above 10 MPa) according to the pressure of oil in the equipment; the sensing optical fiber 8 and the reference optical fiber 9 are respectively provided with the same FBG (fiber Bragg grating) grating, are respectively arranged in the through holes of the end cover 11 corresponding to the compression surface 5, and seal the through holes in the end cover 11 provided with the sensing optical fiber 8 and the reference optical fiber 9; the through hole of the sensing optical fiber 8 is arranged on the compression surface 5 for sealing, and the through hole of the reference optical fiber 9 arranged on the compression surface 5 is not sealed and is arranged as a free end.

The present invention is further described in conjunction with the above-mentioned figures, the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

As shown in fig. 4, one end of the cylindrical shell 2 provided with the M20 × 1.5 external thread 1 is connected with a standard sensor interface of an oil passage 19 to be monitored in the equipment; the ASE light source 13 is used to generate a light beam with a certain wavelength, the light beam passes through the entrance end of the 3db coupler 14 respectively, is divided into two interference lights with the same wavelength, enters the entrance ends of the 1# circulator 15 and the 2# circulator 16 respectively, and enters the sensing fiber 8 and the reference fiber 9 respectively.

The longitudinal vibration of the oil pressure in the oil passage 19 to be monitored acts on both sides of the pressure-receiving surface 5 through the through-hole of the cylindrical housing 2. If the oil longitudinal vibration pressure does not vibrate, the pressures on the two sides of the pressed surface 5 are the same, and the position of the pressed body 4 is unchanged; assuming that the position relationship shown in fig. 4 is that the longitudinal vibration pressure on the left side of the pressure receiving surface 5 is increased, the high-pressure oil flows out through the damping tube 6 through the gap of the damping cone 10, the pressure is decreased, so that the pressure difference on the two sides of the pressure receiving surface 5 is increased, and the high-pressure oil moves rightwards (as shown in fig. 3, the pressure receiving body 4 is also the sensing optical fiber 8 to generate a movement distance of L2), the balancing spring 7 is compressed, the sensing optical fiber 8 is longitudinally compressed, and the reflection wavelength λ 1 of the sensing optical fiber is shifted in the short wave direction; meanwhile, the reference optical fiber 9 is provided with a free end on the pressed surface 5 and is not influenced by the pressure of oil liquid in the longitudinal direction, and the reflection wavelength lambda 2 of the reference optical fiber is not deviated; as the distance of the compression body 4 moving to the right increases, the gap between the damping tube 6 and the damping cone 10 gradually decreases until the compression body is completely closed, and the compression body 4 stops moving under the reaction force of the balance spring 7, so that the sensing optical fiber is prevented from being excessively bent to influence the monitoring accuracy. On the contrary, the left side longitudinal vibration pressure of the pressure receiving surface 5 in the position relationship shown in fig. 4 is reduced, the high-pressure oil flows out through the damping tube 6 through the gap of the damping cone 10, the pressure is reduced, the pressure difference on the two sides of the pressure receiving surface 5 is increased, and the pressure receiving body 4 moves leftwards (as shown in fig. 2, the pressure receiving body 4 also generates a movement distance of L1 for the sensing optical fiber 8), the balance spring 7 is stretched, the sensing optical fiber 8 is longitudinally stretched, and the reflection wavelength λ 1 shifts along the long wave direction; meanwhile, the reference optical fiber 9 is provided with a free end on the pressed surface 5 and is not influenced by the pressure of oil liquid in the longitudinal direction, and the reflection wavelength lambda 2 of the reference optical fiber is not deviated; along with the increase of the leftward movement distance of the pressure-receiving body 4, the gap between the damping tube 6 and the damping cone 10 is gradually increased until the pressures on the two sides of the pressure-receiving surface 5 are the same, and under the action of the reaction force of the balance spring 7, the pressure-receiving body 4 stops moving, so that the sensing optical fiber is prevented from being excessively stretched, and the monitoring accuracy is not affected.

It can be seen that the longitudinal vibration of the oil in the oil passage 19 to be monitored obviously occurs the change process of the FBG reflection center wavelength of the sensing optical fiber 8 in the pressurizing and depressurizing processes acting on the pressure receiving surface 5. The reflection wavelengths of the sensing optical fiber 8 carrying oil vibration and the reference optical fiber 9 respectively enter the optical fiber demodulator 17 through the outlet ends of the 1# circulator 15 and the 2# circulator 16 for demodulation, and then the corresponding signals are analyzed and processed by the computer 18, so that the oil vibration state of the oil channel 19 to be monitored can be obtained, and the vibration monitoring of the oil is realized.

The above description is only for the preferred embodiment of the present invention and is not intended to limit the scope of the present invention, and all equivalent structural changes made by using the contents of the present specification and the drawings, or any other related technical fields, are included in the scope of the present invention.