Belt conveying wheel fault optical fiber detection system based on time division multiplexing

Abstract

The invention discloses a belt conveying wheel fault optical fiber detection system based on time division multiplexing, which is characterized in that pulse square wave light output by a wide-spectrum light source is output by a single-mode optical fiber three-end circulator and sequentially passes through n 1 * 2 optical fiber beam splitters with different light splitting proportions; the main output end of each 1 * 2 optical fiber beam splitter is connected to the input end of the next 1 * 2 optical fiber beam splitter through a section of optical fiber, and the small-proportion output port of each 1 * 2 optical fiber beam splitter is connected with a Sagnac interferometer composed of a 1: 1 1 * 2 single-mode coupler, an optical fiber sensing ring and an optical fiber delay and depolarization ring. The optical fiber sensing ring senses a sound wave signal of one supporting hub of the transmission belt; the width of the pulse light is equal to the light propagation time of a connecting optical fiber between the two 1 * 2 optical fiber beam splitters, the n 1 * 2 optical fiber beam splitters split light according to a specific formula and different light splitting proportions, and one pulse square wave light returns n light pulses with the same amplitude to the three-terminal circulator and is converted into an electric signal by the photoelectric detector.

Description

Technical Field

[0001] The invention relates to an optical fiber acoustic detection system, in particular to an optical fiber detection system for a belt conveyor wheel fault based on time division multiplexing. Background Art

[0002] In the belt transmission system, the hub supporting the belt is prone to serious rotation friction, and even the hub is stuck, causing fire accidents. The current system for detecting this fault is based on the principle of fiber phase time domain reflectometry (phase OTDR) to form a distributed fiber acoustic detection system (DAS). The advantage of DAS is that it can continuously measure sound waves along the optical fiber and is easy to arrange, but it also requires high-cost components such as narrow linewidth lasers and fiber amplifiers, especially when the sound waves of multiple hubs act on the same optical fiber, causing aliasing of sound waves. We noticed that the Sagnac fiber interference ring is an acoustic sensor with very stable performance. One Sagnac ring can only sense the sound waves emitted by one hub, and a series of Sagnac rings are connected to a main optical path using time-division multiplexing, forming a highly reliable fiber acoustic detection system for belt conveyor wheel faults. Summary of the invention

[0003] In order to solve the above problems in the prior art, the present invention proposes a belt conveyor wheel fault optical fiber detection system based on time division multiplexing.

[0004] The present invention can be solved by the following technical solutions:

[0005] A belt conveyor wheel fault optical fiber detection system based on time division multiplexing comprises: a wide-spectrum light source emitting pulsed light signals, a 3-port single-mode optical fiber circulator, a guide optical cable, n 1×2 single-mode optical fiber beam splitters with unequal splitting ratios, n 1×2 single-mode optical fiber couplers with a 1:1 splitting ratio, n single-mode optical fiber sensing rings, n single-mode optical fiber depolarization and delay rings, and a photoelectric detector; the wide-spectrum light source is connected to the input end of the 3-port single-mode optical fiber circulator, the first output end of the 3-port single-mode optical fiber circulator is connected to one end of the guide optical cable, and the second output end of the 3-port single-mode optical fiber circulator is connected to the input end of the 3-port single-mode optical fiber circulator. The photoelectric detectors are connected; the other end of the guide optical cable is connected to the input end of the first 1×2 single-mode optical fiber splitter with unequal splitting ratios, the large-proportion optical power output end of the 1×2 single-mode optical fiber splitter is connected to the input end of the second 1×2 single-mode optical fiber splitter with unequal splitting ratios through a section of optical fiber, the large-proportion optical power output end of the second 1×2 single-mode optical fiber splitter with unequal splitting ratios is connected to the input end of the third 1×2 single-mode optical fiber splitter with unequal splitting ratios through a section of optical fiber, and the lengths of the connecting optical fiber and the connecting optical fiber are equal; the small-proportion optical power output end of the first 1×2 single-mode optical fiber splitter with unequal splitting ratios The first end of the optical fiber coupler is connected to the input end of the first 1×2 single-mode fiber coupler with a 1:1 splitting ratio, and the two output ends of the optical fiber coupler are respectively connected to one end of the first single-mode fiber sensing ring and one end of the first single-mode fiber depolarization and delay ring, and the other end of the first single-mode fiber sensing ring is connected to the other end of the first single-mode fiber depolarization and delay ring; the small-proportion optical power output end of the second 1×2 single-mode fiber beam splitter with unequal splitting ratio is connected to the input end of the second 1×2 single-mode fiber coupler 11 with a 1:1 splitting ratio, and the two output ends of the optical fiber coupler 11 are respectively connected to one end of the second single-mode fiber sensing ring and the second single-mode fiber depolarization and one end of the delay ring, the other end of the second single-mode optical fiber sensing ring is connected to the other end of the second single-mode optical fiber depolarization and delay ring; the small-proportion optical power output end of the third 1×2 single-mode optical fiber beam splitter with unequal splitting ratio is connected to the input end of the third 1×2 single-mode optical fiber coupler with 1:1 splitting ratio, the two output ends of the optical fiber coupler are respectively connected to one end of the third single-mode optical fiber sensing ring and one end of the third single-mode optical fiber depolarization and delay ring, the other end of the third single-mode optical fiber sensing ring is connected to the other end of the third single-mode optical fiber depolarization and delay ring; the above three optical fiber sensing rings, optical fiber depolarization and delay rings are all made of the same optical fiber length;

[0006] The first single-mode optical fiber sensing ring senses the acoustic wave signal of the first hub rotation, the second single-mode optical fiber sensing ring senses the acoustic wave signal of the second hub rotation, and the third single-mode optical fiber sensing ring senses the acoustic wave signal of the third hub rotation; the first hub, the second hub, and the third hub support the transmission belt.

[0007] Furthermore, the pulse width of the pulse light signal emitted by the broadband light source is equal to the time required for the light to pass through the connecting optical fiber of two adjacent 1×2 single-mode optical fiber splitters with unequal splitting ratios, and the splitting power ratio of the two adjacent 1×2 single-mode optical fiber splitters with unequal splitting ratios, the latter splitting ratio and the former splitting ratio satisfy the formula is the ratio of the high-power output end of the n-1th 1×2 single-mode fiber splitter, k n-1 is the ratio of its low-power output end, and the input power has been normalized; each single-mode optical fiber depolarization and delay ring are fully depolarized.

[0008] Furthermore, corresponding to a pulse generated by the wide-spectrum light source, the photodetector receives a series of n pulses with the same pulse width and equal light intensity amplitude when static, and these n pulses correspond to the sound wave signals of n wheel hubs respectively when dynamic.

[0009] Furthermore, when the acoustic wave signal of the hub during normal rotation acts on the corresponding single-mode optical fiber sensor ring, the modulation depth of the Sagnac interferometer is adjusted through appropriate sensor ring design so that the output second multiple of the normal rotation frequency of the hub is a larger value; when the hub rotates lower than the normal speed and reaches the set threshold or even stops, the multiple received by the photodetector also decreases or disappears synchronously.

[0010] Furthermore, the wide spectrum light source adopts an ASE fiber light source and is modulated into pulse light by an acousto-optic modulator.

[0011] Furthermore, the broadband light source adopts a super luminescent semiconductor diode SLD and modulates the light into pulse light using electric current.

[0012] Furthermore, the photodetector adopts a semiconductor avalanche diode APD.

[0013] The beneficial effects achieved by the present invention are:

[0014] The present invention uses n Sagnac fiber interferometers to sense the sound signals of the corresponding n belt conveyor support hubs. The sound signals of each hub will not overlap. A single main optical path and time division multiplexing method can accurately distinguish whether the n hubs rotate normally, including whether the rotation speed of each hub is significantly slowed down or even completely stopped. The system is very stable and reliable, low cost, and has great engineering value in the fields of coal mines and coal-fired power. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a structure diagram of a fiber optic acoustic detection system for belt conveyor pulley failure.

[0016] Figure numerals: broadband light source: 1; single-mode fiber circulator: 2; guide optical cable: 3; first unequal splitting ratio 1×2 single-mode fiber beam splitter: 4; first 1:1 splitting ratio 1×2 single-mode fiber coupler: 5, single-mode fiber sensing ring: 6; single-mode fiber depolarization and delay ring: 7; hub corresponding to sensing ring 6: 8; optical fiber connecting line: 9; second unequal splitting ratio 1×2 single-mode fiber beam splitter: 10; second 1:1 splitting ratio 1×2 single-mode fiber Coupler: 11; single-mode optical fiber sensing ring: 12; single-mode optical fiber depolarization and delay ring: 13; hub corresponding to sensing ring 12: 14; optical fiber connecting line: 15; second unequal splitting ratio 1×2 single-mode optical fiber beam splitter: 16; second 1:1 splitting ratio 1×2 single-mode optical fiber coupler: 17; single-mode optical fiber sensing ring: 18; optical fiber depolarization and delay line: 19; hub corresponding to sensing ring 18: 20; transmission belt: 21; photoelectric detector: 22 DETAILED DESCRIPTION

[0017] The following describes the implementation of the present invention through specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0018] In order to make the description of the purpose, technical solution, advantages, etc. of the present invention clearer and more accurate, the embodiments of the present invention are described in detail below, and examples of the embodiments are given in the form of drawings. It is particularly noted that the exemplary embodiments of the present invention and their descriptions are only used to explain the present invention, but are not intended to limit the design of the present invention.

[0019] like Figure 1 As shown, a belt conveyor wheel fault optical fiber detection system based on time division multiplexing of the present invention, the broadband light source 1 is connected to the input end of the 3-port single-mode optical fiber circulator 2, the first output end of the 3-port single-mode optical fiber circulator 2 is connected to one end of the guide optical cable 3, and the second output end of the 3-port single-mode optical fiber circulator 2 is connected to the photodetector 22;

[0020] Without loss of generality, we discuss a system with three acoustic detection units. Systems with more units are similar:

[0021] The other end of the guide optical cable 3 is connected to the input end of the first unequal splitting ratio 1×2 single-mode optical fiber splitter 4, the large-proportion optical power output end of the 1×2 single-mode optical fiber splitter 4 is connected to the input end of the second unequal splitting ratio 1×2 single-mode optical fiber splitter 10 through a section of optical fiber 9, the large-proportion optical power output end of the second unequal splitting ratio 1×2 single-mode optical fiber splitter 10 is connected to the input end of the third unequal splitting ratio 1×2 single-mode optical fiber splitter 16 through a section of optical fiber 15, and the lengths of the connecting optical fiber 9 and the connecting optical fiber 15 are equal;

[0022] The small-proportion optical power output end of the first unequal-splitting-ratio 1×2 single-mode optical fiber beam splitter 4 is connected to the input end of the first 1:1 splitting-ratio 1×2 single-mode optical fiber coupler 5, and the two output ends of the optical fiber coupler 5 are respectively connected to one end of the first single-mode optical fiber sensing ring 6 and one end of the first single-mode optical fiber depolarization and delay ring 7, and the other end of the first single-mode optical fiber sensing ring 6 is connected to the other end of the first single-mode optical fiber depolarization and delay ring 7; the small-proportion optical power output end of the second unequal-splitting-ratio 1×2 single-mode optical fiber beam splitter 10 is connected to the input end of the second 1:1 splitting-ratio 1×2 single-mode optical fiber coupler 11, and the two output ends of the optical fiber coupler 11 are respectively connected to One end of the second single-mode optical fiber sensing ring 12 is connected to one end of the second single-mode optical fiber depolarization and delay ring 13, and the other end of the second single-mode optical fiber sensing ring 12 is connected to the other end of the second single-mode optical fiber depolarization and delay ring 13; the small-proportion optical power output end of the third unequal splitting ratio 1×2 single-mode optical fiber beam splitter 16 is connected to the input end of the third 1:1 splitting ratio 1×2 single-mode optical fiber coupler 17, and the two output ends of the optical fiber coupler 17 are respectively connected to one end of the third single-mode optical fiber sensing ring 18 and one end of the third single-mode optical fiber depolarization and delay ring 19, and the other end of the third single-mode optical fiber sensing ring 18 is connected to the other end of the third single-mode optical fiber depolarization and delay ring 19;

[0023] The first single-mode optical fiber sensing ring 6 senses the acoustic wave signal of the first hub 8 rotating, the second single-mode optical fiber sensing ring 12 senses the acoustic wave signal of the second hub 14 rotating, and the third single-mode optical fiber sensing ring 18 senses the acoustic wave signal of the third hub 20 rotating; the first hub 8, the second hub 14, and the third hub 20 support the transmission belt 21.

[0024] Among them, the pulse width of the pulse light signal emitted by the wide-spectrum light source is equal to the time required for the light to pass through the connecting optical fiber of two adjacent 1×2 single-mode fiber splitters with unequal splitting ratios, and the splitting power ratio of two adjacent 1×2 single-mode fiber splitters with unequal splitting ratios, and the latter splitting ratio and the previous splitting ratio satisfy the formula is the ratio of the high-power output end of the n-1th 1×2 single-mode fiber splitter, k n-1 is the ratio of its low-power output end, and the input power has been normalized; each single-mode optical fiber depolarization and delay ring are fully depolarized.

[0025] Among them, corresponding to a pulse generated by the wide-spectrum light source, the photodetector 22 receives a series of n pulses with the same pulse width and equal light intensity amplitude in static state, and these n pulses correspond to the sound wave signals of n wheel hubs in dynamic state respectively.

[0026] Among them, when the acoustic wave signal of the hub rotating normally acts on the corresponding single-mode optical fiber sensor ring, the modulation depth of the Sagnac interferometer is adjusted through appropriate sensor ring design, so that the output second frequency doubling of the normal rotation frequency of the hub is a larger value; when the hub rotates lower than the normal speed and reaches the set threshold or even stops, the frequency doubling received by the photoelectric detector also decreases or disappears synchronously.

[0027] The broadband light source 1 adopts an ASE optical fiber light source and is modulated into pulse light by an acousto-optic modulator; the broadband light source 1 may also adopt a super luminescent semiconductor diode SLD and be modulated into pulse light by current.

[0028] The photodetector 21 is a semiconductor avalanche diode APD.

[0029] Example

[0030] In this embodiment, the sampling 1550nm band device, the wide spectrum light source 1 is composed of a Gaussian spectrum fiber light source ASE with a bandwidth of 10nm and an acousto-optic modulator; the fiber circulator 2 is a three-port single-mode device, and the guide cable 3 is 200 meters long; the unequal splitting ratio 1×2 single-mode fiber beam splitters 4, 10, and 16 respectively use 8:92, 10:90, and 12:88 splitting ratio couplers; the 1:1 splitting ratio 1×2 single-mode fiber couplers 5, 11, and 17 all use 1:1 splitting ratio couplers, and the single-mode fiber sensor rings 6, 12, and 18 use 30-meter fiber rings; the single-mode fiber depolarization and delay rings 7, 13, and 19 use 150 meters of optical fiber and are fully depolarized, and are packaged for vibration isolation; the optical fiber connecting line 9 and the optical fiber connecting line 15 are both 30 meters of optical cables; the photodetector 22 uses a semiconductor APD. The three signal sources of the hub driven by three motors act on the sensor rings 6, 12, and 18 respectively. The system can clearly distinguish the wheel hub's speed signal, speed slowdown and rotation stop.

[0031] 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 and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A belt conveyor wheel fault optical fiber detection system based on time division multiplexing, characterized in that: include: A wide spectrum light source emitting pulsed optical signals, a 3-port single-mode optical fiber circulator, a guide optical cable, n 1×2 single-mode optical fiber beam splitters with different splitting ratios, n 1×2 single-mode optical fiber couplers with a splitting ratio of 1:1, n single-mode optical fiber sensing rings, n single-mode optical fiber depolarization and delay rings, and a photodetector; The broadband light source is connected to the input end of a three-port single-mode fiber circulator, a first output end of the three-port single-mode fiber circulator is connected to one end of the guide optical cable, and a second output end of the three-port single-mode fiber circulator is connected to the photodetector; The following is a system with three acoustic detection units, and the same applies to systems with more units: The other end of the guide optical cable is connected to the input end of the first 1×2 single-mode optical fiber splitter with unequal splitting ratio, the large-ratio optical power output end of the 1×2 single-mode optical fiber splitter is connected to the input end of the second 1×2 single-mode optical fiber splitter with unequal splitting ratio through a section of optical fiber, the large-ratio optical power output end of the second 1×2 single-mode optical fiber splitter with unequal splitting ratio is connected to the input end of the third 1×2 single-mode optical fiber splitter with unequal splitting ratio through a section of optical fiber, and the lengths of the connecting optical fiber and the connecting optical fiber are equal; The small-proportion optical power output end of the first 1×2 single-mode fiber beam splitter with unequal splitting ratio is connected to the input end of the first 1×2 single-mode fiber coupler with 1:1 splitting ratio, and the two output ends of the fiber coupler are respectively connected to one end of the first single-mode fiber sensing ring and one end of the first single-mode fiber depolarization and delay ring, and the other end of the first single-mode fiber sensing ring is connected to the other end of the first single-mode fiber depolarization and delay ring; the small-proportion optical power output end of the second 1×2 single-mode fiber beam splitter with unequal splitting ratio is connected to the input end of the second 1×2 single-mode fiber coupler with 1:1 splitting ratio, and the two output ends of the fiber coupler are respectively connected to the second single-mode fiber sensing ring. One end of the ring is connected to one end of the second single-mode optical fiber depolarization and delay ring, and the other end of the second single-mode optical fiber sensing ring is connected to the other end of the second single-mode optical fiber depolarization and delay ring; the small-proportion optical power output end of the third 1×2 single-mode optical fiber beam splitter with unequal splitting ratio is connected to the input end of the third 1×2 single-mode optical fiber coupler with 1:1 splitting ratio, and the two output ends of the optical fiber coupler are respectively connected to one end of the third single-mode optical fiber sensing ring and one end of the third single-mode optical fiber depolarization and delay ring, and the other end of the third single-mode optical fiber sensing ring is connected to the other end of the third single-mode optical fiber depolarization and delay ring; the above three optical fiber sensing rings, optical fiber depolarization and delay rings are all made of the same optical fiber length; The first single-mode optical fiber sensing ring senses the acoustic wave signal of the first hub rotation, the second single-mode optical fiber sensing ring senses the acoustic wave signal of the second hub rotation, and the third single-mode optical fiber sensing ring senses the acoustic wave signal of the third hub rotation; the first hub, the second hub, and the third hub support the transmission belt.

2. A belt conveyor wheel fault optical fiber detection system based on time division multiplexing according to claim 1, characterized in that: The pulse width of the pulse light signal emitted by the broadband light source is equal to the time required for the light to pass through the connecting optical fiber of two adjacent 1×2 single-mode optical fiber beam splitters with unequal splitting ratios, and the splitting power ratio of the two adjacent 1×2 single-mode optical fiber beam splitters with unequal splitting ratios, and the latter splitting ratio satisfies the formula with the former splitting ratio: 1-k n-1 is the ratio of the high-power output end of the n-1th 1×2 single-mode fiber splitter, k n-1 is the ratio of its low power output end, and the input power has been normalized; Each single-mode optical fiber depolarization and delay loop is fully depolarized.

3. A belt conveyor wheel fault optical fiber detection system based on time division multiplexing according to claim 1, characterized in that: Corresponding to a pulse generated by the wide-spectrum light source, the photodetector receives a series of n pulses with the same pulse width and equal light intensity amplitude when static. These n pulses correspond to the sound wave signals of n wheel hubs respectively when dynamic.

4. A belt conveyor wheel fault optical fiber detection system based on time division multiplexing according to claim 1, characterized in that: When the acoustic wave signal of the hub during normal rotation acts on the corresponding single-mode optical fiber sensor ring, the modulation depth of the Sagnac interferometer is adjusted through appropriate sensor ring design so that the output double frequency of the normal rotation frequency of the hub is a larger value; when the hub rotates lower than the normal speed and reaches the set threshold or even stops, the double frequency received by the photodetector also decreases or disappears synchronously.

5. A belt conveyor wheel fault optical fiber detection system based on time division multiplexing according to claim 1, characterized in that: The broadband light source adopts ASE fiber light source and is modulated into pulse light by an acousto-optic modulator.

6. A belt conveyor wheel fault optical fiber detection system based on time division multiplexing according to claim 1, characterized in that: The broadband light source uses a super radiant semiconductor diode (SLD) and modulates it into pulse light using current.

7. A belt conveyor wheel fault optical fiber detection system based on time division multiplexing according to claim 1, characterized in that: The photodetector uses a semiconductor avalanche diode APD.

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