An acoustic monitoring sensor and method for micro-early failure of gears in a strong noise environment

Abstract

The present application belongs to the technical field of gear fault monitoring, and particularly relates to an acoustic monitoring sensor for micro-early gear fault in a strong noise environment, comprising: a protective shell structure, which is provided with a composite noise reduction structure and an acoustic resonance tuning structure inside and located at both ends of the protective shell structure, and a single-electrode triboelectric sensor is arranged in the acoustic resonance tuning structure; the acoustic resonance tuning structure comprises a Helmholtz resonance cavity, and the single-electrode triboelectric sensor is arranged in the Helmholtz resonance cavity; the composite noise reduction structure comprises a cavity coaxially arranged in the protective shell structure, the cavity is provided with a sound absorption structure at an opening thereof, a plurality of sound insulation structures are arranged in the cavity, the sound insulation structures are detachably connected with the cavity, and the distance between adjacent two sound insulation structures is adjustably arranged. The present application can filter out the medium-high frequency and medium-low frequency environmental noise in the strong noise environment, and target-enhance the gear fault characteristic sound signals, thereby adapting to the monitoring requirements under different rotating speed conditions.

Description

Technical Field

[0001] This invention belongs to the field of gear fault monitoring technology, and particularly relates to an acoustic monitoring sensor and method for early micro-faults of gears in high-noise environments. Background Technology

[0002] Gear transmission systems are widely used in aero-engines, wind turbines, rail transit equipment, mining machinery, construction machinery, and industrial automation equipment due to their advantages such as high transmission efficiency, compact structure, and strong load-bearing capacity. As the core component of the transmission system, the operating condition of gears directly affects the safety and reliability of the entire mechanical equipment. During long-term operation, gears are susceptible to alternating loads, impact loads, and complex working conditions, leading to failures such as wear, pitting, scuffing, cracking, and tooth breakage. These failures often manifest as subtle changes in acoustic characteristics in their early stages. Timely detection and maintenance can effectively prevent equipment downtime or major safety accidents.

[0003] Currently, gear fault monitoring technologies mainly include vibration monitoring, temperature monitoring, oil analysis, and acoustic monitoring. Among these, acoustic monitoring technology has gradually become an important research direction for gear condition monitoring due to its advantages such as non-contact measurement, convenient installation, and fast response speed. However, in actual industrial settings, gears typically operate in complex, high-noise environments. The significant background noise generated by motors, bearings, fans, and other mechanical equipment coexists with the gear fault acoustic signal, causing the fault acoustic signal to be submerged and reducing the acoustic monitoring system's ability to identify weak fault characteristics. Furthermore, most existing acoustic monitoring sensors have noise reduction structures designed for fixed frequency bands. When the gear speed changes, the fault characteristic frequency shifts accordingly. Noise reduction structures with fixed parameters struggle to maintain ideal noise reduction effects under different operating conditions. Simultaneously, the fault acoustic signal is prone to energy attenuation when passing through the noise reduction structure, further reducing the intensity of the fault signal received by the sensor. In addition, most of the sensitive elements used for acoustic-to-electric conversion in existing sensors are traditional microphones, which have limited ability to distinguish weak fault sound signals in strong noise environments. Although the resonant enhancement structure used in some studies can amplify sound signals of specific frequencies, its resonant frequency is also fixed, making it difficult to match with the fault characteristic frequency after the shift under varying operating conditions. Summary of the Invention

[0004] The purpose of this invention is to provide an acoustic monitoring sensor and method for early gear failures in high-noise environments, in order to solve the above-mentioned problems.

[0005] To achieve the above objectives, the present invention provides the following solution: An acoustic monitoring sensor for early gear failures in high-noise environments includes: a protective housing structure, wherein a composite noise reduction structure and an acoustic resonance tuning structure are disposed within the protective housing structure, the composite noise reduction structure and the acoustic resonance tuning structure are respectively located at both ends of the protective housing structure, and a single-electrode triboelectric sensor is disposed within the acoustic resonance tuning structure. The acoustic resonance tuning structure includes a Helmholtz resonant cavity, and the single-electrode triboelectric sensor is disposed inside the Helmholtz resonant cavity. The composite noise reduction structure includes a cavity, which is coaxially disposed within the protective shell structure. A sound-absorbing structure is provided at the opening of the cavity, and multiple sound-insulating structures are provided inside the cavity. The sound-insulating structures are detachably connected to the cavity, and the distance between two adjacent sound-insulating structures is adjustable.

[0006] Preferably, the sound-absorbing structure includes a sound-absorbing material support, which is disposed in the cavity. The top of the sound-absorbing material support is provided with sound-absorbing material, and the top surface of the sound-absorbing material is flush with the top of the cavity.

[0007] Preferably, the sound insulation structure includes a sound insulation film assembly support, the sound insulation film assembly support includes an outer ring, the outer ring is coaxially disposed in the cavity, the outer ring is detachably connected to the cavity, a plurality of second threaded holes are circumferentially spaced at the outer edge of the top surface of the outer ring, an upper cover ring is coaxially disposed on the top surface of the outer ring, the upper cover ring is circumferentially spaced at a plurality of threaded through holes, the plurality of threaded through holes are corresponding one-to-one with the plurality of second threaded holes, a screw passes through the threaded through hole and is threaded into the second threaded hole to fix the outer ring and the upper cover ring together, and a sound insulation film is disposed between the outer ring and the upper cover ring.

[0008] Preferably, at least one groove is provided on the outer side wall of the cavity, and multiple grooves are equally spaced circumferentially. At least one first threaded hole is provided radially on the outer circumferential surface of the outer ring and the sound-absorbing material support. Multiple first threaded holes are provided in correspondence with multiple grooves. Screws pass through the grooves and are threadedly connected to the first threaded holes to fix the outer ring, the sound-absorbing material support and the cavity.

[0009] Preferably, the inner wall of the protective shell structure is provided with an internal thread, which is close to one end of the protective shell structure. The outer wall of the cavity is provided with an external thread, which cooperates with the internal thread to connect the cavity to the protective shell structure.

[0010] Preferably, the inner sidewall of the protective shell structure is provided with a plurality of slots at equal intervals in the circumferential direction. The slots are located at the end of the protective shell structure away from the internal thread. The outer sidewall of the Helmholtz resonant cavity is fixed with a plurality of buckles at equal intervals in the circumferential direction. The plurality of buckles are provided in a one-to-one correspondence with the plurality of slots and are adapted to connect the Helmholtz resonant cavity to the protective shell structure.

[0011] Preferably, the outer circumferential surface of the protective shell structure is covered with sound-insulating material.

[0012] Preferably, an internal support is provided inside the Helmholtz resonant cavity, and the single-electrode triboelectric sensor is fixed on the internal support.

[0013] Preferably, the single-electrode triboelectric sensor includes a flexible substrate layer, an electrode layer is disposed on one side of the flexible substrate layer, a spacer is disposed on the other side of the flexible substrate layer, and a friction layer is disposed on the side of the spacer away from the flexible substrate layer.

[0014] An acoustic monitoring method for early micro-faults in gears under high noise conditions, based on the aforementioned acoustic monitoring sensor for early micro-faults in gears under high noise conditions, comprises the following steps: The operating condition information of the gear to be monitored is obtained, and the fault characteristic frequency and environmental noise spectrum of the gear to be monitored are determined based on the operating condition information. Based on the fault characteristic frequency and the ambient noise spectrum, the distance between two adjacent sound insulation structures is adjusted so that the ambient noise spectrum is within the attenuation frequency band of the composite noise reduction structure. Based on the fault characteristic frequency, the Helmholtz resonator is configured so that the resonant frequency of the Helmholtz resonator corresponds to the fault characteristic frequency. The original sound signal generated by gear operation enters the composite noise reduction structure. The sound absorption structure attenuates the mid-to-high frequency environmental noise in the original sound signal, and multiple sound insulation structures attenuate the mid-to-low frequency environmental noise. The fault characteristic sound signal is transmitted to the Helmholtz resonant cavity through the composite noise reduction structure. The Helmholtz resonant cavity targets and enhances the fault characteristic acoustic signal. The enhanced fault characteristic acoustic signal acts on the single-electrode triboelectric sensor, which generates an electrical signal and outputs it to the electrical signal analysis equipment. Electrical signal analysis equipment analyzes the acquired electrical signals and extracts fault feature information to identify gear fault conditions.

[0015] Compared with the prior art, the present invention has the following advantages and technical effects: This invention integrates a composite noise reduction structure and an acoustic resonance tuning structure into a single unit through a protective shell structure. A single-electrode triboelectric sensor is placed within the acoustic resonance tuning structure. The original acoustic signal generated by gear operation sequentially passes through a sound-absorbing structure and multiple sound-insulating structures within the composite noise reduction structure. The sound-absorbing structure attenuates mid-to-high frequency environmental noise in the original acoustic signal, while the multiple sound-insulating structures attenuate mid-to-low frequency environmental noise. Simultaneously, by adjusting the distance between adjacent sound-insulating structures, the fault characteristic acoustic signal passes through the composite noise reduction structure with low energy loss and is transmitted to the acoustic resonance tuning structure. After entering the Helmholtz resonant cavity, the resonant frequency corresponds to the fault characteristic frequency through the configuration of the cavity volume, neck length, and neck cross-sectional area, achieving targeted enhancement of the acoustic signal at that frequency. The enhanced acoustic signal acts on the single-electrode triboelectric sensor located inside the Helmholtz resonant cavity, driving it to generate an electrical signal output, thus replacing a traditional microphone to achieve highly sensitive detection of weak acoustic signals. When changes in gear speed cause a shift in the fault characteristic frequency, the sensor can be adapted to the new operating conditions by adjusting the spacing of the sound insulation structure and reconfiguring the parameters of the Helmholtz resonant cavity. This enables the effective acquisition and accurate identification of early gear micro-fault acoustic signals under different speed conditions. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort: Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a front sectional view of the present invention; Figure 3 This is a left-side sectional view of the present invention; Figure 4 for Figure 2 A magnified view of a section at point I; Figure 5 This is a left view of the cavity in this invention; Figure 6 This is the internal structure of the cavity in this invention; Figure 7 This is a schematic diagram of the overall structure of the sound-absorbing material support in this invention; Figure 8 This is a cross-sectional view of the sound-absorbing material support in this invention; Figure 9 This is an overall schematic diagram of the sound insulation film assembly support in this invention; Figure 10 This is a front sectional view of the sound insulation film assembly support in this invention; Figure 11 This is a left-side cross-sectional view of the sound insulation film assembly support in this invention; Figure 12 This is an overall perspective view of the protective outer shell structure in this invention; Figure 13 This is a schematic diagram of the internal structure of the protective outer shell structure in this invention; Figure 14 This is an overall schematic diagram of the acoustic resonance tuning structure in this invention; Figure 15 This is a schematic diagram of the internal structure of the acoustic resonance tuning structure in this invention; Figure 16 This is a schematic diagram of the single-electrode triboelectric sensor in this invention; Figure 17 This is a schematic diagram illustrating the principle of the present invention; The components include: 1. Composite noise reduction structure; 2. Protective shell structure; 201. Internal thread; 202. Slot; 203. Sound insulation material; 3. Acoustic resonance tuning structure; 301. Helmholtz resonant cavity; 302. Internal support; 303. Buckle; 4. Cavity; 401. Slide groove; 402. External thread; 5. Sound-absorbing material support; 501. First threaded hole; 6. Sound insulation film assembly support; 601. Top cover ring; 602. Outer ring; 603. Threaded through hole; 604. Second threaded hole; 7. Sound-absorbing material; 8. Sound insulation film; 9. Single-electrode triboelectric sensor; 901. Friction layer; 902. Spacer support; 903. Flexible base layer; 904. Electrode layer. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] Reference Figures 1 to 17 The present invention discloses an acoustic monitoring sensor for early gear micro-faults in a strong noise environment, comprising: a protective shell structure 2, a composite noise reduction structure 1 and an acoustic resonance tuning structure 3 disposed inside the protective shell structure 2, the composite noise reduction structure 1 and the acoustic resonance tuning structure 3 being located at opposite ends of the protective shell structure 2, and a single-electrode triboelectric sensor 9 disposed inside the acoustic resonance tuning structure 3. The acoustic resonance tuning structure 3 includes a Helmholtz resonant cavity 301, and a single-electrode triboelectric sensor 9 is disposed inside the Helmholtz resonant cavity 301. The composite noise reduction structure 1 includes a cavity 4, which is coaxially arranged inside the protective shell structure 2. A sound-absorbing structure is provided at the opening of the cavity 4, and multiple sound-insulating structures are provided inside the cavity 4. The sound-insulating structures are detachably connected to the cavity 4, and the distance between two adjacent sound-insulating structures can be adjusted.

[0020] When the acoustic monitoring sensor is in use, the original acoustic signal generated by the gear operation enters from one end where the composite noise reduction structure 1 is located. It passes through the sound-absorbing structure at the opening of the cavity 4 and multiple sound-insulating structures inside the cavity 4 in sequence, and the environmental noise is filtered out step by step. The fault characteristic acoustic signal passes through the composite noise reduction structure 1 with low energy loss and is transmitted to the acoustic resonance tuning structure 3 at the other end through the internal channel of the protective shell structure 2. After entering the Helmholtz resonant cavity 301, the sound wave corresponding to the fault characteristic frequency resonates in the resonant cavity, and the sound pressure amplitude is targeted and enhanced. The enhanced fault acoustic signal acts on the single-electrode triboelectric sensor 9 set inside the Helmholtz resonant cavity 301, driving the triboelectric sensor to generate an electrical signal output, thereby achieving highly sensitive monitoring of the early micro-fault acoustic signal of the gear in a strong noise environment. By setting the sound insulation structure to be detachably connected to the cavity 4 and the spacing between adjacent sound insulation structures to be adjustable, the sensor can flexibly adjust the noise reduction frequency band according to the fault characteristic frequency under different speed conditions, solving the problem that fixed structures are difficult to adapt to changes in working conditions.

[0021] Further optimization of the scheme: the sound-absorbing structure includes a sound-absorbing material support 5, which is set inside the cavity 4. The top of the sound-absorbing material support 5 is provided with sound-absorbing material 7, and the top surface of the sound-absorbing material 7 is flush with the top of the cavity 4.

[0022] The sound-absorbing material support 5 is placed inside the cavity 4, and the sound-absorbing material 7 is laid on top of it, with the top surface of the sound-absorbing material 7 flush with the top of the cavity 4. In use, the original sound signal first enters the sound-absorbing material 7, and the sound wave undergoes viscous friction and heat exchange in the pores of the material, effectively attenuating mid-to-high frequency environmental noise, while the fault characteristic sound signal continues to propagate into the cavity 4 through the sound-absorbing material 7, achieving the first stage of noise reduction at the sensor inlet.

[0023] Further optimization of the scheme: The sound insulation structure includes a sound insulation film assembly support 6, which includes an outer ring 602. The outer ring 602 is coaxially disposed inside the cavity 4 and is detachably connected to the cavity 4. Multiple second threaded holes 604 are evenly spaced around the outer edge of the top surface of the outer ring 602. An upper cover ring 601 is coaxially disposed on the top surface of the outer ring 602. Multiple threaded through holes 603 are evenly spaced around the top surface of the upper cover ring 601. The multiple threaded through holes 603 are corresponding to the multiple second threaded holes 604. Screws pass through the threaded through holes 603 and are threaded into the second threaded holes 604 to fix the outer ring 602 and the upper cover ring 601. A sound insulation film 8 is disposed between the outer ring 602 and the upper cover ring 601.

[0024] When in use, the sound insulation film assembly bracket 6 holds and fixes the sound insulation film 8 between the outer ring 602 and the upper cover ring 601, with the outer ring 602 coaxially positioned within the cavity 4. Multiple sound insulation films 8 are arranged sequentially along the direction of sound signal propagation. The air layer between adjacent sound insulation films 8 forms an acoustic coupling structure. Sound waves undergo multiple reflections, transmissions, and interferences as they pass through the multi-layered sound insulation films, effectively attenuating low- and mid-frequency environmental noise in the membrane-air layer coupling system. The upper cover ring 601 and the outer ring 602 can be easily disassembled and assembled via a screw connection between the threaded through hole 603 and the second threaded hole 604, facilitating the replacement and maintenance of the sound insulation film 8.

[0025] To further optimize the design, at least one groove 401 is provided on the outer wall of the cavity 4, and multiple grooves 401 are equally spaced around the periphery. At least one first threaded hole 501 is provided radially on the outer circumferential surface of the outer ring 602 and the outer circumferential surface of the sound-absorbing material support 5. Multiple first threaded holes 501 are provided in a one-to-one correspondence with multiple grooves 401. Screws pass through the grooves 401 and are threadedly connected to the first threaded holes 501 to fix the outer ring 602, the sound-absorbing material support 5 and the cavity 4.

[0026] The groove 401 on the outer wall of the cavity 4 is engaged with the first threaded hole 501 on the sound-absorbing material support 5 and the outer ring 602 by screws. In use, the operator can adjust the axial position of the sound-absorbing material support 5 and each sound insulation film group support 6 in the cavity 4 along the direction of the groove 401 according to the target fault characteristic frequency and the ambient noise spectrum under the current working conditions. This changes the compression state of the sound-absorbing material 7 and the thickness of the air layer between adjacent sound insulation films 8, so as to realize the continuous adjustment of the noise reduction frequency band in a wide frequency range, and enable the sensor to flexibly adapt to the monitoring needs under different speeds and working conditions.

[0027] To further optimize the design, an internal thread 201 is provided on the inner wall of the protective shell structure 2, with the internal thread 201 close to one end of the protective shell structure 2. An external thread 402 is provided on the outer wall of the cavity 4, and the external thread 402 cooperates with the internal thread 201 to connect the cavity 4 to the protective shell structure 2.

[0028] The protective shell structure 2 is connected to the cavity 4 via an internal thread 201 and an external thread 402. In use, the composite noise reduction structure 1 is firmly fixed to one end of the protective shell structure 2. The threaded connection ensures the airtightness and structural stability of the sound signal propagation channel, preventing sound signal leakage or additional reflection at the interface, and ensuring that the fault characteristic sound signal after noise reduction can be stably transmitted to the subsequent acoustic resonance tuning structure 3.

[0029] To further optimize the design, multiple slots 202 are provided at equal intervals around the inner sidewall of the protective shell structure 2. The slots 202 are located at the end of the protective shell structure 2 away from the internal thread 201. Multiple buckles 303 are fixedly connected at equal intervals around the outer sidewall of the Helmholtz resonant cavity 301. The multiple buckles 303 are set and matched one-to-one with the multiple slots 202, connecting the Helmholtz resonant cavity 301 to the protective shell structure 2.

[0030] The groove 202 on the inner wall of the protective shell structure 2 forms a limiting fit with the snap 303 on the outer side of the Helmholtz resonant cavity 301. In use, the acoustic resonance tuning structure 3 can be quickly installed to the other end of the protective shell structure 2 or removed from it, which facilitates the maintenance and replacement of the Helmholtz resonant cavity 301 and the internal single-electrode triboelectric sensor 9, or the replacement of resonant cavities with different geometric parameters according to different fault characteristic frequencies. The snap-fit ​​connection ensures the axial limiting and radial positioning accuracy after installation, ensuring that the acoustic resonance tuning structure 3 does not shift during operation.

[0031] The design was further optimized by covering the outer circumferential surface of the protective shell structure 2 with sound-insulating material 203.

[0032] The outer periphery of the protective housing structure 2 is covered with sound-insulating material 203. In use, the sound-insulating material 203 forms a sound barrier outside the sensor, effectively blocking external environmental noise from being transmitted from the side wall of the protective housing structure 2 into the sound signal propagation channel. This prevents the fault sound signal, after being processed by the composite noise reduction structure 1, from being contaminated by external noise again during transmission, thus ensuring the purity of the sound signal transmitted in the internal channel of the protective housing structure 2.

[0033] In a further optimized design, an internal support 302 is provided inside the Helmholtz resonant cavity 301, and a single-electrode triboelectric sensor 9 is fixed on the internal support 302.

[0034] An internal support 302 within the Helmholtz resonant cavity 301 secures the single-electrode triboelectric sensor 9 inside. During use, the single-electrode triboelectric sensor 9 is precisely positioned within the sound pressure concentration area of ​​the resonant cavity, allowing the amplified fault sound signal to act most effectively on the sensor surface. The fixed installation method ensures that the sensor does not shift or vibrate during operation, guaranteeing the stability of the acoustic-electric conversion process and the consistency of the signal output.

[0035] Further optimization of the scheme: the single-electrode triboelectric sensor 9 includes a flexible substrate layer 903, an electrode layer 904 is provided on one side of the flexible substrate layer 903, a spacer bracket 902 is provided on the other side of the flexible substrate layer 903, and a friction layer 901 is provided on the side of the spacer bracket 902 away from the flexible substrate layer 903.

[0036] When the single-electrode triboelectric sensor 9 is in use, the amplified fault acoustic signal acts on one side of the flexible substrate 903. Under the periodic sound pressure, the flexible substrate 903 reciprocates, causing the friction layer 901 to move synchronously. The relative distance between the friction layer 901 and the reference structure on the opposite side changes periodically, causing a change in the electric field generated by the surface static charge. The induced charges in the electrode layer 904 are redistributed accordingly, thereby outputting a voltage or current signal corresponding to the fault acoustic signal, realizing a stable conversion of the acoustic signal to an electrical signal. The spacer bracket 902 ensures that the friction layer 901 and the flexible substrate 903 always maintain a preset initial gap, allowing the sensor to maintain a stable working state during vibration.

[0037] An acoustic monitoring method for early micro-faults in gears under high noise environments, based on an acoustic monitoring sensor for early micro-faults in gears under high noise environments, comprises the following steps: The operating condition information of the gear to be monitored is obtained, and the fault characteristic frequency and environmental noise spectrum of the gear to be monitored are determined based on the operating condition information. Based on the fault characteristic frequency and the ambient noise spectrum, the distance between two adjacent sound insulation structures is adjusted so that the ambient noise spectrum is within the attenuation frequency band of the composite noise reduction structure 1. Based on the fault characteristic frequency, the Helmholtz resonator 301 is configured so that the resonant frequency of the Helmholtz resonator 301 corresponds to the fault characteristic frequency. The original sound signal generated by the gear operation enters the composite noise reduction structure 1. The sound absorption structure attenuates the mid-to-high frequency environmental noise in the original sound signal, and multiple sound insulation structures attenuate the mid-to-low frequency environmental noise. The fault characteristic sound signal is transmitted to the Helmholtz resonant cavity 301 through the composite noise reduction structure 1. The Helmholtz resonant cavity 301 targets and enhances the fault characteristic acoustic signal. The enhanced fault characteristic acoustic signal acts on the single-electrode triboelectric sensor 9, which generates an electrical signal and outputs it to the electrical signal analysis device. Electrical signal analysis equipment analyzes the acquired electrical signals and extracts fault feature information to identify gear fault conditions.

[0038] An acoustic monitoring sensor for gear faults in high-noise environments includes a composite noise reduction structure 1, a protective shell structure 2, and an acoustic resonance tuning structure 3. The composite noise reduction structure 1 uses porous sound-absorbing materials and sound-insulating film materials to filter out environmental noise and reduce energy loss during the propagation of gear fault acoustic signals. The acoustic resonance tuning structure 3 optimizes parameters such as the Helmholtz cavity opening direction, cavity volume, and neck length to match its resonance frequency with the target fault signal frequency, thereby achieving targeted enhancement of the gear fault acoustic signal. The protective shell structure 2 connects the composite noise reduction structure 1 and the acoustic resonance tuning structure 3 and reduces external noise interference during the transmission of acoustic signals.

[0039] The composite noise reduction structure 1 includes a cavity 4, a sound-absorbing material support 5, a sound-insulating film assembly support 6, a sound-absorbing material 7, and a sound-insulating film 8. The sound-absorbing material support 5 is disposed inside the cavity 4 and is fixedly connected to the cavity 4 through a first threaded hole 501. The sound-absorbing material 7 is laid on the surface of the sound-absorbing material support 5 and is coaxially fitted with the sound-absorbing material support 5. The sound-insulating film assembly support 6 is connected to the lower part of the sound-absorbing material support 5 inside the cavity 4 through the first threaded hole 501, and the two are coaxially fitted. The sound-insulating film 8 is placed in the inner groove of the sound-insulating film assembly support 6. The protective outer shell structure 2 is located inside... One side of the protective shell structure 2 has an internal thread 201 that connects to the external thread 402 of the cavity 4 of the composite noise reduction structure 1; the other side of the protective shell structure 2 has an L-shaped slot 202 that forms a limiting fit with the buckle 303 in the acoustic resonance tuning structure 3, enabling quick installation and disassembly between the structures; the outer surface of the protective shell structure 2 is covered with sound insulation material 203; the acoustic resonance tuning structure 3 has a Helmholtz resonant cavity 301 inside; the lower end of the outer wall of the acoustic resonance tuning structure 3 has several buckles 303 that form a limiting fit with the slot 202 on one side of the protective shell structure 2. A single-electrode triboelectric sensor 9 is plugged into and connected to the internal support 302 of the Helmholtz resonant cavity 301.

[0040] The cavity 4 has grooves 401 extending along its height on both sides. A through channel is formed in the middle of the groove 401, and the channel is formed along the length of the groove. The width of the channel is adapted to the nominal diameter of the first threaded hole 501 used to connect the sound-absorbing material support 5 and the sound-insulating film assembly support 6, so that the screw can pass through the channel and be threadedly connected to the corresponding support, thereby coaxially fixing the sound-absorbing material support 5 and the sound-insulating film assembly support 6 inside the cavity 4.

[0041] The sound-absorbing material support 5 and the sound-insulating film assembly support 6 can be adjusted in position along the slide groove 401 during installation, thereby making the spacing between the sound-insulating film assembly supports 6 adjustable. By adjusting the spacing, it is possible to adapt to gear fault characteristic signals under different speed conditions, reduce mid-to-low frequency environmental noise in strong noise environments, and reduce energy loss during the propagation of gear fault sound signals.

[0042] According to the mass-air-mass resonance theory, the thickness d of the air layer between the two membranes affects the system's resonant frequency, which satisfies the following: Natural frequency Hz Speed ​​of sound in air air density Thickness of the air layer between the two membranes First diaphragm surface density Second diaphragm surface density Sound-absorbing material 7 is laid on the surface of sound-absorbing material support 5 and coaxially fitted with it. Sound-absorbing material 7 is prepared using a cryogenic casting process with precursor solutions of different mass fractions of PU, PS, PVA, PP, and PLA, resulting in porous sound-absorbing materials of varying materials and thicknesses (2-10 mm). The microstructure of the porous sound-absorbing material is characterized using SEM and XRD to obtain parameters such as porosity and pore size distribution. The influence of different parameters on the sound absorption coefficient of the porous material is investigated using an acoustic impedance tube, thus achieving the absorption of high-frequency environmental noise in high-noise environments.

[0043] The sound insulation film assembly support 6 is a ring structure component, including an upper cover ring 601 and an outer ring 602 coaxially arranged. The outer ring 602 has first threaded holes 501 on both sides, which are connected to the sliding grooves 401 on both sides of the cavity 4 by screws. The upper cover ring 601 has several radial threaded through holes 603, and the outer ring 602 has second threaded holes 604 corresponding to the threaded through holes 603. The screws pass through the threaded through holes 603 in sequence and cooperate with the second threaded holes 604 to realize the fixed connection between the upper cover ring 601 and the outer ring 602. The upper cover ring 601 and the outer ring 602 are axially limited and radially positioned by a stepped nesting structure. The sound insulation film 8 is placed in the inner groove of the outer ring 602. By adjusting the spacing between the sound insulation film assemblies, the natural frequency of the system is changed, so as to match the gear fault characteristic signals under different speed conditions, and at the same time reduce the energy loss during the propagation of the gear fault sound signal.

[0044] The sound insulation film 8 is prepared by air-flow spinning process, solvent-induced process and other processes to prepare films of different materials; by adjusting the weight of the mass block by 0.1-0.5g and the position of the mass block (center, middle and edge), films of different mass block states are obtained; films of different states are placed in acoustic impedance tubes to test the changes in sound insulation performance of different films under different film parameters; the acoustic impedance tube is used to test the effect of different film quantity and position on the sound insulation performance of the film.

[0045] The protective outer shell structure 2 is a cylindrical shell. One end of its inner wall has an internal thread 201 structure, which is used to achieve threaded connection with the external thread 402 on the cavity 4 in the composite noise reduction structure 1. The other end of the inner wall has several slots 202 structures, which are used to form a limiting fit with the buckle 303 in the acoustic resonance tuning structure 3 to achieve quick installation and disassembly between the structures. Its outer surface is covered with sound insulation material 203, which can be made of rubber damping material, composite sound insulation felt or other sound insulation materials, to reduce the interference of external environmental noise on the sound signal transmission process.

[0046] The acoustic resonance tuning structure 3 is a cylindrical shell with a through opening at one end. A cavity structure connected to the interior of the shell is formed on the side wall of the shell, and the cavity and the outside are connected through the opening to form a Helmholtz resonant cavity 301. The Helmholtz resonant cavity 301 generates a resonant response to the sound wave signal corresponding to the frequency of the gear fault signal. The gear fault signal is amplified and energy is concentrated in the cavity. By absorbing or modulating the sound wave of the corresponding frequency, the gear fault sound signal is targetedly amplified. The single-electrode triboelectric sensor 9 is plugged into the internal bracket 302 of the acoustic resonance tuning structure 3.

[0047] The parameters such as the opening direction, cavity volume, and neck length of the Helmholtz resonant cavity 301 were optimized. The theoretically optimized Helmholtz resonant cavity 301 was prepared using 3D printing technology. When the frequency of the acoustic signal is close to the resonant frequency of the Helmholtz resonant cavity 301, the air column at the neck opening resonates with the air inside the resonant cavity, thereby enhancing the sound pressure amplitude of the corresponding frequency sound wave and increasing the energy of the target fault characteristic acoustic signal.

[0048] The above structure enables targeted enhancement of the acoustic signal corresponding to the frequency of the target fault signal, while suppressing acoustic signals at non-target frequencies, thereby improving the detection capability of gear fault acoustic signals in high-noise environments.

[0049] To analyze and optimize the resonance characteristics, the natural frequency can be estimated using Helmholtz resonance theory, as shown in the following expression: Resonant frequency Speed ​​of sound Cavity volume Actual neck length Radius of the resonant cavity opening End correction length The single-electrode triboelectric sensor 9 includes a flexible substrate layer 903, an electrode layer 904 is disposed on one side of the flexible substrate layer 903, a spacer bracket 902 is disposed on the other side of the flexible substrate layer 903, and a friction layer 901 is disposed on the side of the spacer bracket 902 away from the flexible substrate layer 903.

[0050] The friction layer 901 can be made of polytetrafluoroethylene (PTFE) or fluorinated ethylene propylene copolymer (FEP); the flexible base layer 903 can be made of polyimide (PI) film or polyethylene terephthalate (PET) film; and the electrode layer 904 can be made of copper, aluminum, or silver.

[0051] During operation, the fault acoustic signal, processed by the composite noise reduction structure 1 and enhanced by the Helmholtz resonant cavity 301, acts on the surface of the flexible substrate layer 903. Under the periodic sound pressure, the flexible substrate layer 903 reciprocates. Supported by the spacer bracket 902, it maintains a preset initial gap structure, limiting the vibration displacement of the friction layer 901 within a set range, thus achieving stable periodic gap changes. The vibration of the flexible substrate layer 903 drives the friction layer 901 to move synchronously, causing the gap between the friction layer 901 and the reference electrode to change periodically. Since the surface of the friction layer 901 has pre-accumulated static charge, the gap change causes a change in the electric field distribution, which in turn drives the transfer of induced charges in the electrode layer 904, forming voltage and current signals corresponding to the fault acoustic signal output between the electrode layer 904 and the external circuit.

[0052] With the above structure, the single-electrode triboelectric sensor 9 can convert the fault sound signal enhanced by the Helmholtz resonant cavity into an electrical signal, thereby realizing the detection and acquisition of gear fault sound information.

[0053] During operation of the single-electrode triboelectric sensor 9, the flexible substrate layer 903 vibrates under sound pressure, causing a change in the gap distance between the friction layer 901 and the relatively positioned structure, resulting in a change in the equivalent capacitance; under short-circuit conditions, its transferred charge satisfies: Charge transferred under short-circuit conditions Surface charge density of the friction layer : Width of triboelectric unit Length of triboelectric unit Part 1: Equivalent Capacitance Part Two: Equivalent Capacitance The gap distance between the friction layer and the oppositely arranged structure The charge transfer efficiency of the single-electrode triboelectric sensor 9 satisfies: Charge transfer efficiency Charge transferred under short-circuit conditions Surface charge density of the friction layer : Width of triboelectric unit Length of triboelectric unit Part 1: Equivalent Capacitance Part Two: Equivalent Capacitance The gap distance between the friction layer and the oppositely arranged structure In the open-circuit state, the output voltage of the single-electrode triboelectric sensing unit satisfies: Open-circuit output voltage Surface charge density of the friction layer : Width of triboelectric unit Length of triboelectric unit Part 1: Equivalent Capacitance Part Two: Equivalent Capacitance Part Three: Equivalent Capacitance The equivalent capacitances vary with the gap changes caused by the vibration of the flexible substrate.

[0054] An acoustic monitoring method for early micro-faults in gears under high-noise environments, the method specifically includes the following: First, information on the rotational speed, number of teeth, load status, lubrication status, and operating environment of the gear to be monitored is acquired. Based on the gear's current operating conditions, the corresponding target fault characteristic frequency range is determined. The raw acoustic signals generated during gear operation include gear fault acoustic signals and environmental noise. The gear rotational frequency, meshing frequency, and their harmonics and sidebands change with rotational speed. The amplitude and spectral distribution of the fault acoustic signal are also affected by load, lubrication status, fault type, and fault severity. Meanwhile, the frequency distribution of environmental noise generated by motors, bearings, fans, and other mechanical equipment also varies under different operating scenarios.

[0055] Based on the current operating conditions of the gear, the characteristic frequency of the target fault, and the ambient noise spectrum in the operating scenario, the spacing between the sound insulation film groups in the composite noise reduction structure 1 is adjusted. Specifically, the corresponding sound insulation film support is moved along the slide groove 401 to change the distance between adjacent sound insulation films 8, and then fixed with screws after being moved to the preset position. When the distance between adjacent sound insulation films 8 changes, the thickness of the air layer between the films and the propagation distance of the sound waves between the multiple sound insulation films change accordingly, thereby changing the reflection, transmission, interference, and energy dissipation state of the sound waves between the sound insulation films and the air layer, thus adjusting the frequency response characteristics of the sound insulation film group.

[0056] For different speeds, loads, and environmental noise scenarios, a pre-established correspondence between gear operating conditions, environmental noise spectrum, and sound insulation film spacing can be established. When the gear speed changes, causing shifts in rotational frequency, meshing frequency, and related fault characteristic frequencies, a film spacing corresponding to the current operating condition is selected to attenuate the frequency range where environmental noise is concentrated, while reducing energy loss of the target fault characteristic sound signal when passing through the composite noise reduction structure.

[0057] After the composite sound signal generated by the gear operation enters the composite noise reduction structure 1, it first passes through the porous sound-absorbing material 7. When the sound wave enters the interior of the porous sound-absorbing material 7, the air in the pores of the material undergoes reciprocating motion under the action of sound pressure. The sound energy is consumed through the viscous friction and heat exchange between the air and the pore walls, thereby mainly attenuating the mid-to-high frequency environmental noise in the composite sound signal.

[0058] The sound signal processed by the porous sound-absorbing material 7 continues to pass through the multi-layer sound insulation film 8 and the air layer formed between the adjacent sound insulation films 8 to form a multi-layer film-air layer acoustic coupling system. The acoustic coupling system includes multiple mass-air-mass coupling units arranged sequentially along the sound propagation direction.

[0059] By adjusting the position of the support 6 of the sound insulation film assembly, the air layer thicknesses d1, d2, and d3 can be changed respectively, thereby altering the equivalent stiffness, natural frequency, damping characteristics, and acoustic impedance of the sound insulation film assembly. This allows the sound transmission characteristics of the composite noise reduction structure 1 to adapt to changes in gear operating conditions and the ambient noise spectrum. For different speeds, loads, and operating scenarios, appropriate combinations of air layer thicknesses can be selected to achieve greater attenuation in the concentrated frequency band of ambient noise and reduce the energy attenuation of the target fault characteristic sound signal during propagation. The porous sound-absorbing material 7 and the sound insulation film 8 together form a frequency-band composite noise reduction path, balancing environmental noise suppression and fault characteristic sound signal transmission.

[0060] Based on the target fault characteristic frequency corresponding to the current operating condition, the cavity volume, neck length, and neck cross-sectional area of ​​the Helmholtz resonator 301 are configured so that the resonant frequency of the Helmholtz resonator 301 corresponds to the target fault characteristic frequency. When the frequency of the acoustic signal entering the Helmholtz resonator 301 approaches its resonant frequency, the air column inside the neck vibrates reciprocally under sound pressure excitation, and the air inside the cavity undergoes periodic compression and expansion, causing acoustic energy near the target frequency to accumulate in the cavity, thereby increasing the sound pressure amplitude of the corresponding fault characteristic acoustic signal and achieving targeted enhancement of the target fault characteristic frequency.

[0061] The enhanced fault acoustic signal acts on a single-electrode triboelectric sensor 9 located inside the Helmholtz resonant cavity 301. Periodic sound pressure acts on the flexible substrate 903, causing the friction layer 901, the flexible substrate 903, and the electrode layer 904 to vibrate together, resulting in a periodic change in the relative distance between the friction layer 901 and the reference electrode. This change in relative distance alters the electric field distribution between the friction layer 901 and the reference electrode, and redistributes the induced charges in the electrode layer 904. Consequently, the electrode layer 904 outputs an electrical signal corresponding to the fault acoustic signal, thus converting the fault acoustic signal into an electrical signal.

[0062] Finally, the electrical signal output by the single-electrode triboelectric sensor 9 is acquired, and time-domain and frequency-domain analysis methods are used to extract the rotational frequency, meshing frequency, harmonics, sidebands, and periodic impact components. The extracted fault feature information is correlated with the current gear speed, load state, and operating conditions to determine whether the gear has faults such as wear, pitting, cracks, or broken teeth.

[0063] When gear speed, load, lubrication status or operating environment changes, the target fault characteristic frequency range and environmental noise spectrum are redefined, and the thickness of each air layer in the sound insulation film group is adjusted according to the pre-established correspondence. At the same time, the parameters of the Helmholtz resonant cavity 301 adapted to the target fault characteristic frequency are configured to meet the acoustic monitoring needs of gear faults under different operating conditions and application scenarios.

[0064] Through the synergistic effect of composite noise reduction structure, protective shell structure, acoustic resonance tuning structure and single-electrode triboelectric sensor, an integrated acoustic monitoring process is achieved that suppresses environmental noise, enhances gear fault signal frequency, and performs acoustic-electric conversion.

[0065] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0066] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An acoustic monitoring sensor for early micro-faults in gears under high-noise environments, characterized in that, include: The protective shell structure (2) is provided with a composite noise reduction structure (1) and an acoustic resonance tuning structure (3). The composite noise reduction structure (1) and the acoustic resonance tuning structure (3) are located at the two ends of the protective shell structure (2). A single-electrode triboelectric sensor (9) is provided in the acoustic resonance tuning structure (3). The acoustic resonance tuning structure (3) includes a Helmholtz resonant cavity (301), and the single-electrode triboelectric sensor (9) is disposed in the Helmholtz resonant cavity (301); The composite noise reduction structure (1) includes a cavity (4), which is coaxially disposed within the protective shell structure (2). A sound-absorbing structure is provided at the opening of the cavity (4), and multiple sound-insulating structures are provided inside the cavity (4). The sound-insulating structures are detachably connected to the cavity (4), and the distance between two adjacent sound-insulating structures can be adjusted.

2. The acoustic monitoring sensor for early gear failures in high-noise environments according to claim 1, characterized in that: The sound-absorbing structure includes a sound-absorbing material support (5), which is disposed in the cavity (4). The top of the sound-absorbing material support (5) is provided with sound-absorbing material (7), and the top surface of the sound-absorbing material (7) is flush with the top of the cavity (4).

3. The acoustic monitoring sensor for early gear failures in high-noise environments according to claim 2, characterized in that: The sound insulation structure includes a sound insulation film assembly support (6), the sound insulation film assembly support (6) includes an outer ring (602), the outer ring (602) is coaxially disposed in the cavity (4), the outer ring (602) is detachably connected to the cavity (4), a plurality of second threaded holes (604) are circumferentially spaced at the outer edge of the top surface of the outer ring (602), an upper cover ring (601) is coaxially disposed on the top surface of the outer ring (602), a plurality of threaded through holes (603) are circumferentially spaced at the upper cover ring (601), the plurality of threaded through holes (603) are correspondingly disposed to the plurality of second threaded holes (604), a screw passes through the threaded through hole (603) and is threadedly connected in the second threaded hole (604) to fix the outer ring (602) and the upper cover ring (601), and a sound insulation film (8) is disposed between the outer ring (602) and the upper cover ring (601).

4. An acoustic monitoring sensor for early gear failures in high-noise environments according to claim 3, characterized in that: At least one groove (401) is provided on the outer wall of the cavity (4). Multiple grooves (401) are circumferentially spaced. At least one first threaded hole (501) is provided radially on the outer circumferential surface of the outer ring (602) and the sound-absorbing material support (5). Multiple first threaded holes (501) are provided one-to-one with multiple grooves (401). Screws pass through the grooves (401) and are threadedly connected to the first threaded holes (501) to fix the outer ring (602), the sound-absorbing material support (5) and the cavity (4).

5. An acoustic monitoring sensor for early gear faults in high-noise environments according to claim 1, characterized in that: The inner wall of the protective shell structure (2) is provided with an internal thread (201), which is close to one end of the protective shell structure (2). The outer wall of the cavity (4) is provided with an external thread (402), which cooperates with the internal thread (201) to connect the cavity (4) to the protective shell structure (2).

6. An acoustic monitoring sensor for early gear failures in high-noise environments according to claim 5, characterized in that: The inner sidewall of the protective shell structure (2) is provided with a plurality of slots (202) at equal intervals in the circumferential direction. The slots (202) are located at the end of the protective shell structure (2) away from the internal thread (201). The outer sidewall of the Helmholtz resonant cavity (301) is fixed with a plurality of buckles (303) at equal intervals in the circumferential direction. The plurality of buckles (303) are provided and matched one-to-one with the plurality of slots (202) to connect the Helmholtz resonant cavity (301) to the protective shell structure (2).

7. An acoustic monitoring sensor for early gear failures in high-noise environments according to claim 1, characterized in that: The outer circumferential surface of the protective shell structure (2) is covered with sound insulation material (203).

8. An acoustic monitoring sensor for early gear failures in high-noise environments according to claim 1, characterized in that: An internal support (302) is provided inside the Helmholtz resonant cavity (301), and the single-electrode triboelectric sensor (9) is fixed on the internal support (302).

9. An acoustic monitoring sensor for early gear faults in high-noise environments according to claim 1, characterized in that: The single-electrode triboelectric sensor (9) includes a flexible substrate layer (903), an electrode layer (904) is provided on one side of the flexible substrate layer (903), a spacer bracket (902) is provided on the other side of the flexible substrate layer (903), and a friction layer (901) is provided on the side of the spacer bracket (902) away from the flexible substrate layer (903).

10. An acoustic monitoring method for early gear failures in high-noise environments, based on the acoustic monitoring sensor for early gear failures in high-noise environments as described in any one of claims 1-9, characterized in that, The steps are as follows: Obtain the operating condition information of the gear to be monitored, and determine the fault characteristic frequency and environmental noise spectrum of the gear to be monitored based on the operating condition information; Based on the fault characteristic frequency and the ambient noise spectrum, the distance between two adjacent sound insulation structures is adjusted so that the ambient noise spectrum is within the attenuation frequency band of the composite noise reduction structure (1). Based on the fault characteristic frequency, the Helmholtz resonator (301) is configured so that the resonant frequency of the Helmholtz resonator (301) corresponds to the fault characteristic frequency; The original sound signal generated by the gear operation enters the composite noise reduction structure (1). The sound absorption structure attenuates the mid-to-high frequency environmental noise in the original sound signal, and multiple sound insulation structures attenuate the mid-to-low frequency environmental noise. The fault characteristic sound signal is transmitted to the Helmholtz resonant cavity (301) through the composite noise reduction structure (1). The Helmholtz resonant cavity (301) targets and enhances the fault characteristic acoustic signal. The enhanced fault characteristic acoustic signal acts on the single-electrode triboelectric sensor (9). The single-electrode triboelectric sensor (9) generates an electrical signal and outputs it to the electrical signal analysis device. Electrical signal analysis equipment analyzes the acquired electrical signals and extracts fault feature information to identify gear fault conditions.

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