A low-voltage wire harness insulation failure early warning structure based on conductive coating and optical fiber sensing

Abstract

The application discloses a kind of based on conductive coating and optical fiber sensing's automobile low-voltage wire harness insulation failure early warning structure, it is related to vehicle electrical control system technical field, including: low-voltage wire harness body, the low-voltage wire harness body includes low-voltage conductor, composite insulation layer and end fitting, the composite insulation layer is covered in the surface of low-voltage conductor, the end fitting is arranged at the both ends of low-voltage wire harness body, for with vehicle inner wall device surface socket connection.The application constructs conductive coating resistance and optical fiber grating deformation dual-sensing fusion monitoring system, both through resistance mutation accurate identification insulation cracking, damp, breakage and other dominant faults, also through small deformation monitoring capture microcrack, slight aging and other early hidden failures, simultaneously through double-parameter cross-checking logic, solve the problem that single optical fiber sensing cannot distinguish vehicle normal bending and insulation abnormal wear, realize full-cycle full-dimension fault monitoring.

Description

Technical Field

[0001] This invention relates to the field of vehicle electrical control system technology, and specifically to an early warning structure for insulation failure of automotive low-voltage wiring harnesses based on conductive coating and fiber optic sensing. Background Technology

[0002] Low-voltage wiring harnesses in automobiles are the core transmission carriers of the entire vehicle's electrical system, widely used in body control, smart cockpits, and driver assistance systems, undertaking critical functions in power distribution and signal transmission. Traditional wiring harness insulation monitoring devices mainly include manual inspection equipment, single conductive coating monitoring systems, and single fiber optic deformation sensing systems. Their core function is to detect faults such as insulation layer damage and short circuits, preventing leakage, burning, or even vehicle spontaneous combustion accidents caused by insulation failure, thus ensuring vehicle driving safety and stable operation of the electrical system.

[0003] However, under the complex and harsh conditions of continuous body vibration, high and low temperature cycling, high frequency bending, and oil and salt spray corrosion, traditional insulation monitoring devices have limitations due to their single monitoring technology. Manual inspection can only identify obvious faults after the fact, a single conductive coating cannot identify early hidden failures such as micro-cracks and slight aging, and a single fiber optic sensor cannot distinguish between normal bending and insulation wear, thus failing to achieve full-cycle and full-dimensional fault monitoring. At the same time, they have weak anti-interference capabilities and low intelligence, and are susceptible to false alarms and missed alarms due to vehicle electromagnetic interference and environmental temperature and humidity. Furthermore, they lack fault classification and early warning capabilities and accurate location capabilities, failing to meet the technical requirements of high reliability and full life cycle safety monitoring for modern automobiles. Summary of the Invention

[0004] This invention provides an early warning structure for insulation failure of automotive low-voltage wiring harnesses based on conductive coating and fiber optic sensing, in order to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A low-voltage wiring harness insulation failure early warning structure for automobiles based on conductive coating and fiber optic sensing includes: a low-voltage wiring harness body, comprising a low-voltage conductor, a composite insulation layer, and end connectors; the composite insulation layer covering the surface of the low-voltage conductor; and end connectors located at both ends of the low-voltage wiring harness body for connection to sockets on the surface of devices on the vehicle's interior wall; a composite monitoring layer embedded within the composite insulation layer, composed of a conductive monitoring coating and a flexible fiber optic sensing strip; and an early warning mechanism embedded within the end connectors, comprising a conductive coating monitoring component and an optical fiber. Sensing and monitoring components; conductive coating monitoring components, including a constant voltage power supply unit, a resistance acquisition unit, and a signal transmission unit, are electrically connected to the electrodes at both ends of the conductive monitoring coating, continuously outputting a constant voltage, and acquiring the coating resistance value change in real time across the entire area to identify obvious faults such as insulation cracking, moisture absorption, and damage; fiber optic sensing and monitoring components, including a fiber optic grating sensing unit and an optical signal demodulation unit, are connected to a flexible fiber optic sensing strip to acquire data on local extrusion, friction, bending stress, and minute deformation of the wire bundle in real time, accurately capturing early latent failures such as micro-cracks and slight wear in the insulation layer.

[0006] A further improvement of the technical solution of the present invention is that the composite insulation layer includes an inner basic insulation layer and an outer wear-resistant insulation layer, wherein the inner basic insulation layer is made of modified PP material.

[0007] A further improvement of the technical solution of the present invention is that: the outer wear-resistant insulation layer is made of polyurethane, and a 0.1mm annular installation gap is reserved between the double insulation layers to provide installation space for the composite monitoring layer; the surface of the outer wear-resistant insulation layer is covered with a wear-resistant reinforcement layer at the installation bend.

[0008] A further improvement of the technical solution of the present invention is that the thickness of the conductive monitoring coating is controlled at 0.05-0.1 mm, and a flexible conductive polymer material is used to fully cover the outer surface of the inner base insulation layer.

[0009] A further improvement of the technical solution of the present invention is that: the flexible optical fiber sensing strip has a flat structure, and the non-bent parts are spirally wound around the outside of the conductive monitoring coating with a pitch of 5-8 mm, and the bent parts are spirally wound around the outside of the conductive monitoring coating with a pitch of 2-4 mm. Fiber grating sensing units are arranged on the surface of the flexible optical fiber sensing strip at equal intervals of 10-15 cm.

[0010] A further improvement of the technical solution of the present invention is that the early warning mechanism further includes a signal processing and early warning module, which is communicatively connected to the fiber optic sensing and monitoring component and the fiber optic sensing and monitoring component, and has a built-in data filtering unit and a dual-parameter fusion hierarchical early warning algorithm. It can filter vehicle electromagnetic vibration and temperature and humidity interference, fuse resistance data and deformation data to distinguish between normal operating conditions and fault operating conditions, output three-level early warning signals, and interconnect with the vehicle VCU and cloud platform.

[0011] A further improvement of the technical solution of the present invention is that the dual-parameter fusion judgment logic of the signal processing and early warning module is as follows: when the deformation data collected by the flexible optical fiber sensing strip is lower than the first threshold, it is determined that the vehicle is bending normally; when the deformation data exceeds the first threshold and the resistance of the conductive monitoring coating does not change characteristically, it is determined that the wire harness is abnormally squeezed; when the deformation data exceeds the second threshold and the resistance changes accordingly, it is determined that the insulation layer has failed.

[0012] A further improvement of the technical solution of the present invention is that the three-level warning signals output by the signal processing and warning module are as follows: the first-level warning corresponds to slight aging and minor wear of the insulation layer, and is only indicated by text on the vehicle instrument panel; the second-level warning corresponds to local cracking and moisture, triggering an audible and visual alarm and prompting the driver to have it repaired as soon as possible; the third-level warning corresponds to severe damage and short circuit risk, and at the same time sends a signal to the vehicle VCU to activate the graded power-off protection mechanism.

[0013] A further improvement of the technical solution of the present invention is that: the optical signal demodulation unit identifies the characteristic wavelength offset of the fiber optic grating sensing unit at different positions, and combines the spiral winding pitch of the flexible optical fiber sensing strip with the grating layout spacing to accurately locate the specific interval of insulation failure, with a positioning accuracy of ≤15cm.

[0014] A further improvement of the technical solution of the present invention is that: the end connector adopts a modular pluggable structure, the warning mechanism is integrated into the end connector, and the signal processing and warning module transmits the warning level, fault location and insulation health data to the vehicle-mounted VCU and cloud platform in real time, so as to realize online monitoring and remote operation and maintenance management of the entire life cycle of the wiring harness.

[0015] Due to the adoption of the above technical solution, the technical progress achieved by this invention compared to the prior art is as follows: This invention provides an early warning structure for insulation failure in automotive low-voltage wiring harnesses based on conductive coatings and fiber optic sensing. By constructing a dual-sensor fusion monitoring system integrating conductive coating resistance and fiber optic grating deformation, it accurately identifies explicit faults such as insulation cracking, moisture absorption, and damage through resistance mutations, while capturing early latent faults such as micro-cracks and slight aging through minute deformation monitoring. Simultaneously, through dual-parameter cross-validation logic, it solves the problem that single fiber optic sensing cannot distinguish between normal vehicle bending and abnormal insulation wear, achieving full-cycle, multi-dimensional fault monitoring. The built-in data filtering unit effectively shields against vehicle electromagnetic interference and temperature and humidity fluctuations, significantly reducing false alarm and missed alarm rates. A three-level hierarchical early warning system is constructed, matching differentiated handling strategies, and combined with distributed gratings, it achieves precise fault location within a ≤15cm range. The early warning mechanism is modularly integrated into the end connector, without altering the original wiring harness structure and assembly process, enabling full-lifecycle online monitoring and remote maintenance, fully meeting the high reliability and safety requirements of modern automobiles. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the main structure of the present invention; Figure 2 This is a schematic diagram of the decomposed state structure of the present invention; Figure 3 This is a schematic diagram of the internal layered structure of the present invention; Figure 4 This is a schematic diagram of the flexible optical fiber sensing strip structure of the present invention; Figure 5 This is a schematic diagram of the transverse cross-sectional structure of the present invention; Figure 6 For the present invention Figure 2 Enlarged structural diagram at point A in the middle; Figure 7 This is a flowchart of the early warning process of the present invention.

[0017] In the diagram: 11. Low-voltage conductor; 12. Inner base insulation layer; 13. Outer wear-resistant insulation layer; 14. Annular mounting gap; 15. Wear-resistant reinforcement layer; 16. End connector; 21. Conductive monitoring coating; 22. Flexible fiber optic sensing strip; 311. Constant voltage power supply unit; 312. Resistance acquisition unit; 313. Signal transmission unit; 321. Optical signal demodulation unit; 322. Fiber optic grating sensing unit; 331. Signal processing and early warning module. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to embodiments: Example 1, as Figures 1-7As shown, this invention provides an automotive low-voltage wiring harness insulation failure early warning structure based on conductive coating and fiber optic sensing, comprising: a low-voltage wiring harness body, including a low-voltage conductor 11, a composite insulation layer, and end connectors 16, wherein the composite insulation layer covers the surface of the low-voltage conductor 11, and the end connectors 16 are disposed at both ends of the low-voltage wiring harness body for connection to the surface sockets of devices on the vehicle interior wall; a composite monitoring layer, embedded inside the composite insulation layer, composed of a conductive monitoring coating 21 and a flexible fiber optic sensing strip 22; and an early warning mechanism, embedded inside the end connectors 16, including a conductive coating monitoring component and a fiber optic sensing element. The sensing and monitoring components include: a conductive coating monitoring component, comprising a constant voltage power supply unit 311, a resistance acquisition unit 312, and a signal transmission unit 313, which are electrically connected to the electrodes at both ends of the conductive monitoring coating, continuously outputting a constant voltage, and acquiring the coating resistance value change in real time across the entire area to identify obvious faults such as insulation cracking, moisture absorption, and damage; and a fiber optic sensing and monitoring component, comprising a fiber optic grating sensing unit 322 and an optical signal demodulation unit 321, which is connected to a flexible fiber optic sensing strip 22 to acquire data on local extrusion, friction, bending stress, and minute deformation of the wire bundle in real time, accurately capturing early latent failures such as micro-cracks and slight wear in the insulation layer.

[0019] It should be noted that: the low-voltage conductor 11 uses multi-strand stranded oxygen-free copper wire to transmit vehicle-mounted 12V / 24V low-voltage power and CAN / LIN bus control signals; the composite insulation layer provides double electrical insulation and mechanical protection for the low-voltage conductor; the end connector 16 adopts an automotive-grade injection-molded structure to achieve reliable electrical connection and mechanical fixation between the wiring harness and the vehicle-mounted ECU, sensors, and actuators; the composite monitoring layer provides a dual physical sensing carrier for in-situ monitoring of insulation failure and is integrally molded with the wiring harness body; the conductive monitoring coating 21 reflects conductive damage such as cracking, water ingress, and breakage of the insulation layer through a sudden change in its own resistance value; the flexible optical fiber sensing strip 22 reflects mechanical damage such as micro-deformation, micro-cracks, and localized wear of the insulation layer through the wavelength shift of the fiber optic grating; and the early warning mechanism provides data acquisition and signal processing for the system. The core functions of monitoring and early warning output are integrated into the end connector without occupying extra space; the constant voltage power supply unit 311 outputs a stable DC voltage of 5V±0.1V to provide constant excitation for the conductive monitoring coating; the resistance acquisition unit 312 adopts a high-precision 16-bit ADC to acquire the global resistance value of the conductive monitoring coating in real time at a sampling frequency of 10Hz; the signal transmission unit 313 adopts a differential signal transmission method to achieve anti-interference transmission of monitoring data and control signals; the fiber optic sensing monitoring component realizes distributed real-time perception of the mechanical state of the insulation layer; the fiber optic grating sensing unit 322, based on the Bragg diffraction principle, converts local deformation and stress changes into characteristic wavelength shifts of reflected light; the optical signal demodulation unit 321 adopts a wavelength scanning method to convert optical signals into processable digital electrical signals with a demodulation accuracy of 1pm.

[0020] In this embodiment, by integrating a dual-sensor system of conductive coating resistance monitoring and fiber optic grating deformation monitoring into the wire harness body and embedding an early warning mechanism in the end connector, a basic hardware architecture for insulation failure early warning is constructed, realizing the synchronous monitoring of explicit and implicit faults and solving the problem of the lack of dimensions in traditional single monitoring technology.

[0021] Example 2, as Figures 1-7 As shown, based on Embodiment 1, the present invention provides a technical solution: Preferably, the composite insulation layer includes an inner base insulation layer 12 and an outer wear-resistant insulation layer 13. The inner base insulation layer 12 is made of modified PP material, and the outer wear-resistant insulation layer 13 is made of polyurethane material. A 0.1mm annular installation gap 14 is reserved between the two insulation layers to provide installation space for the composite monitoring layer. The surface of the outer wear-resistant insulation layer 13 is covered with a wear-resistant reinforcing layer 15 at the bending points. The thickness of the conductive monitoring coating 21 is controlled at 0.05-0.1mm, and a flexible conductive polymer material is used to fully cover the outer surface of the inner base insulation layer 12. The flexible fiber optic sensing strip 22 has a flat structure, and the non-bending points are... A 5-8mm pitch spiral is wound around the outside of the conductive monitoring coating 21, and a 2-4mm pitch spiral is wound around the outside of the conductive monitoring coating 21 after bending. Fiber grating sensing units 322 are arranged on the surface of the flexible fiber optic sensing strip 22 at equal intervals of 10-15cm. The early warning mechanism also includes a signal processing and early warning module 331. The signal processing and early warning module 331 is communicatively connected to the fiber optic sensing monitoring component and the fiber optic sensing monitoring component, and has a built-in data filtering unit and a dual-parameter fusion hierarchical early warning algorithm. It can filter vehicle electromagnetic vibration and temperature and humidity interference, fuse resistance data and deformation data to distinguish between normal operating conditions and fault operating conditions, output three-level early warning signals, and interconnect with the vehicle VCU and cloud platform.

[0022] It should be noted that: the inner basic insulation layer 12 is 0.3-0.5mm thick and made of modified polypropylene with a temperature resistance rating of 125℃, providing the first layer of reliable insulation protection for the low-voltage conductor; the outer wear-resistant insulation layer 13 is 0.4-0.6mm thick and made of thermoplastic polyurethane with a Shore hardness of 85A, possessing excellent wear resistance, oil resistance, aging resistance, and low-temperature resistance; the annular installation gap 14 is precisely controlled at 0.1mm±0.02mm, providing stress-free installation space for the composite monitoring layer and preventing fiber optic deformation from affecting monitoring accuracy; the wear-resistant reinforcement layer 15 is a 0.2mm thick nylon 66 braided layer, covering all installation bends of the wiring harness (such as door hinges, dashboard corners, etc.), significantly improving the wear resistance life at bends; the conductive monitoring coating 21 uses a flexible coating doped with carbon nanotubes. The conductive polymer composite material has an elongation at break of ≥300%, allowing it to bend freely with the wire bundle without cracking or falling off. The flexible optical fiber sensing strip 22 adopts a flat cladding structure with a thickness of 0.1mm, which is more tightly wound and less prone to slippage compared to circular optical fibers, resulting in better monitoring consistency. The 5-8mm winding pitch in the non-bending area ensures the uniformity of monitoring, while the 2-4mm dense winding pitch in the bending area improves the monitoring sensitivity in high-risk areas. The fiber optic grating sensing unit 322 has a grating length of 10mm, a reflectivity of ≥90%, and a wavelength spacing of ≥2nm between the centers of adjacent gratings to avoid crosstalk. The signal processing and early warning module 331 adopts an automotive-grade 32-bit MCU with a built-in adaptive Kalman filter algorithm, which can effectively filter noise signals caused by engine vibration, motor electromagnetic interference, and temperature and humidity fluctuations from -40℃ to 125℃.

[0023] In this embodiment, the structural design of double-insulated, ultra-thin composite monitoring layer embedded in the middle does not change the original outer diameter and assembly process of the wiring harness, and is fully compatible with existing automotive wiring harness mass production lines. The combination of encrypted optical fiber winding at the bend and wear-resistant reinforcement layer significantly improves the monitoring sensitivity and structural durability of the high-frequency bending area. The built-in data filtering unit effectively shields the interference of complex electromagnetic environment and temperature and humidity fluctuations in the vehicle, laying the foundation for accurate fault diagnosis in the future.

[0024] Example 3, as Figures 1-7As shown, based on Embodiment 1, the present invention provides a technical solution: Preferably, the dual-parameter fusion judgment logic of the signal processing and early warning module 331 is as follows: when the deformation data collected by the flexible optical fiber sensing strip 22 is lower than the first threshold, it is determined that the vehicle is bending normally during driving; when the deformation data exceeds the first threshold and the resistance of the conductive monitoring coating 21 shows no characteristic change, it is determined that the wiring harness is abnormally squeezed; when the deformation data exceeds the second threshold and the resistance undergoes a corresponding sudden change, it is determined that the insulation layer has failed. The three-level early warning signals output by the signal processing and early warning module 331 are as follows: the first-level early warning corresponds to slight aging and micro-wear of the insulation layer, and only provides text prompts through the vehicle instrument panel; the second-level early warning corresponds to local cracking and moisture, triggering sound and light. The alarm is triggered and the driver is prompted to have the equipment repaired as soon as possible. The three-level warning corresponds to severe damage and short circuit risk. At the same time, a signal is sent to the vehicle-mounted VCU to activate the graded power-off protection mechanism. The optical signal demodulation unit 321 identifies the characteristic wavelength offset of the fiber optic grating sensing unit 322 at different positions. Combined with the spiral winding pitch of the flexible optical fiber sensing tape 22 and the grating layout spacing, it accurately locates the specific area of ​​insulation failure with a positioning accuracy of ≤15cm. The end connector 16 adopts a modular pluggable structure. The warning mechanism is integrated into the end connector 16. The signal processing and warning module 331 transmits the warning level, fault location and insulation health data to the vehicle-mounted VCU and cloud platform in real time to realize online monitoring and remote operation and maintenance management of the entire life cycle of the wiring harness.

[0025] It should be noted that in the dual-parameter fusion judgment logic, the first threshold is set to 1.5 times the maximum value of normal bending deformation, and the second threshold is set to the critical deformation value when the insulation layer develops micro-cracks. When the deformation data is between the first and second thresholds and the resistance does not change, it is determined that the wiring harness is experiencing abnormal friction with surrounding components. In the three-level warning signal, the first level warning is a yellow warning, which only displays "Slight wear on the wiring harness, recommended for next maintenance inspection" on the vehicle's central control screen; the second level warning is an orange warning, which simultaneously triggers the flashing of the yellow indicator light on the instrument panel and the intermittent alarm of the buzzer; the third level warning is a red warning, which triggers the constant illumination of the red indicator light on the instrument panel and the... The buzzer sounds a continuous alarm and sends an emergency power-off command to the vehicle's VCU via the CAN bus; the positioning algorithm of the optical signal demodulation unit 321 is: fault location = grating number × grating spacing + (wavelength offset / unit deformation wavelength offset) × winding pitch / 2π; the modular pluggable end connector adopts the AMP standard interface, and the warning mechanism is connected to the wiring harness body through gold-plated pins with a contact resistance ≤ 5mΩ. During maintenance, the warning module can be replaced separately without replacing the entire wiring harness; the cloud platform can realize big data analysis of batch wiring harness health data of the same model, identify common fault modes, and provide data support for wiring harness design optimization.

[0026] In this embodiment, the dual-parameter cross-validation judgment logic completely solves the industry pain point that a single fiber optic sensor cannot distinguish between normal deformation and insulation failure, significantly reducing the system's false alarm rate. Through a three-level graded early warning and graded power-off protection mechanism, it achieves graded safe handling of faults and avoids safety accidents caused by wiring harness short circuits and ablation. Through precise fault location of ≤15cm and remote operation and maintenance in the cloud, it greatly reduces the difficulty of after-sales repair and operation and maintenance costs, and fully meets the technical requirements for safety monitoring of the entire life cycle of intelligent connected vehicles.

[0027] The working principle of this automotive low-voltage wiring harness insulation failure early warning structure based on conductive coating and fiber optic sensing will be explained in detail below.

[0028] like Figures 1-7 As shown, after the system is powered on and initialized, the constant voltage power supply unit 311 outputs a constant DC voltage to both ends of the conductive monitoring coating 21. The resistance acquisition unit 312 acquires the resistance value of the entire coating area in real time at a frequency of 10Hz and sends it to the signal processing and early warning module 331 through the signal transmission unit 313. At the same time, the optical signal demodulation unit 321 emits broadband probe light to the flexible optical fiber sensing strip 22, receives the characteristic optical signals reflected by each fiber grating sensing unit 322, demodulates the deformation and stress data at different locations, and transmits them synchronously to the signal processing and early warning module 331.

[0029] The signal processing and early warning module 331 first filters noise signals caused by vehicle engine vibration, motor electromagnetic interference, and ambient temperature and humidity fluctuations through the built-in adaptive filtering unit. Then, it starts the dual-parameter fusion judgment logic: when only periodic deformation data below the first threshold is collected, it is judged as bending deformation caused by normal vehicle driving or door opening and closing, and the system maintains a silent monitoring state; when the deformation data exceeds the first threshold but the resistance of the conductive monitoring coating 21 does not change characteristically, it is judged as abnormal compression or friction of the wiring harness, and a first-level warning is output, with only text prompts displayed on the vehicle instrument panel; when the deformation data exceeds the second threshold and the resistance changes accordingly, it is judged as a fault of cracking, dampness, or damage to the insulation layer.

[0030] Depending on the severity of the fault, the signal processing and early warning module 331 outputs a corresponding level of early warning signal and performs linked operations: Level 1 warning corresponds to slight aging and minor wear of the insulation layer, prompting the driver to check during the next maintenance; Level 2 warning corresponds to local cracking and moisture, triggering the vehicle's audible and visual alarm and prompting the driver to bring the vehicle to the repair station for inspection as soon as possible; Level 3 warning corresponds to severe damage and short circuit risk, immediately sending a signal to the vehicle's VCU to activate the graded power-off protection mechanism, prioritizing the disconnection of power to non-safety-related circuits while retaining power to core systems such as braking and steering, ensuring the vehicle can safely travel to the repair area.

[0031] Meanwhile, the optical signal demodulation unit 321 identifies the number of the fiber optic grating sensing unit 322 that has experienced a characteristic wavelength shift, and calculates the specific range of insulation failure (positioning accuracy ≤15cm) by combining the spiral winding pitch of the flexible optical fiber sensing tape 22 with the grating layout spacing. It then uploads the warning level, fault location, and insulation health trend data to the vehicle-mounted VCU and cloud platform in real time, achieving online monitoring, fault warning, and remote operation and maintenance management throughout the entire lifecycle of the wiring harness. During long-term use of the wiring harness, the wear-resistant reinforcement layer 15 at the bend of the outer wear-resistant insulation layer 13 effectively resists wear caused by repeated bending. The densely wound flexible optical fiber sensing tape 22 at the bend enhances the monitoring sensitivity of this high-risk area, ensuring that micron-level microcracks can be detected in time, providing early warning of insulation failure risks from the source.

[0032] The present invention has been described in detail above. However, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, any modifications or improvements that do not depart from the spirit of the present invention are within the scope of protection of the present invention.

Claims

1. A pre-warning structure for insulation failure of automotive low-voltage wiring harnesses based on conductive coating and fiber optic sensing, characterized in that: include: The low-voltage wiring harness body includes a low-voltage conductor (11), a composite insulation layer and an end connector (16). The composite insulation layer covers the surface of the low-voltage conductor (11), and the end connector (16) is disposed at both ends of the low-voltage wiring harness body for connection to the surface socket of the vehicle interior wall device. The composite monitoring layer is embedded inside the composite insulating layer and is composed of a conductive monitoring coating (21) and a flexible optical fiber sensing strip (22). The early warning mechanism is embedded inside the end connector (16) and includes a conductive coating monitoring component and an optical fiber sensing monitoring component; The conductive coating monitoring component includes a constant voltage power supply unit (311), a resistance acquisition unit (312), and a signal transmission unit (313). The whole is electrically connected to the electrodes at both ends of the conductive monitoring coating, continuously outputs a constant voltage, and collects the changes in coating resistance values ​​in real time across the entire area to identify obvious faults such as insulation cracking, moisture absorption, and damage. The fiber optic sensing and monitoring component includes a fiber optic grating sensing unit (322) and an optical signal demodulation unit (321), which is connected to a flexible fiber optic sensing strip (22) to collect data on local extrusion, friction, bending stress and minute deformation of the wire bundle in real time, and accurately capture early latent failures such as microcracks and slight wear in the insulation layer.

2. The automotive low-voltage wiring harness insulation failure early warning structure based on conductive coating and fiber optic sensing according to claim 1, characterized in that: The composite insulation layer includes an inner basic insulation layer (12) and an outer wear-resistant insulation layer (13), with the inner basic insulation layer (12) made of modified PP material.

3. The automotive low-voltage wiring harness insulation failure early warning structure based on conductive coating and fiber optic sensing according to claim 2, characterized in that: The outer wear-resistant insulation layer (13) is made of polyurethane. A 0.1mm annular installation gap (14) is reserved between the two layers of insulation to provide installation space for the composite monitoring layer. The outer wear-resistant insulation layer (13) is covered with a wear-resistant reinforcement layer (15) at the bending point.

4. The automotive low-voltage wiring harness insulation failure early warning structure based on conductive coating and fiber optic sensing according to claim 1, characterized in that: The thickness of the conductive monitoring coating (21) is controlled at 0.05-0.1 mm, and a flexible conductive polymer material is used to fully cover the outer surface of the inner basic insulation layer (12).

5. The automotive low-voltage wiring harness insulation failure early warning structure based on conductive coating and fiber optic sensing according to claim 1, characterized in that: The flexible fiber optic sensing strip (22) has a flat structure. The non-bent parts are spirally wound around the outside of the conductive monitoring coating (21) with a pitch of 5-8 mm, and the bent parts are spirally wound around the outside of the conductive monitoring coating (21) with a pitch of 2-4 mm. Fiber grating sensing units (322) are arranged on the surface of the flexible fiber optic sensing strip (22) at equal intervals of 10-15 cm.

6. The automotive low-voltage wiring harness insulation failure early warning structure based on conductive coating and fiber optic sensing according to claim 1, characterized in that: The early warning mechanism also includes a signal processing and early warning module (331). The signal processing and early warning module (331) is connected to the fiber optic sensing and monitoring component and the fiber optic sensing and monitoring component respectively. It has a built-in data filtering unit and a dual-parameter fusion hierarchical early warning algorithm, which can filter vehicle electromagnetic vibration and temperature and humidity interference, fuse resistance data and deformation data to distinguish between normal working conditions and fault working conditions, output three-level early warning signals, and interconnect with the vehicle VCU and cloud platform.

7. The automotive low-voltage wiring harness insulation failure early warning structure based on conductive coating and fiber optic sensing according to claim 1, characterized in that: The dual-parameter fusion judgment logic of the signal processing and early warning module (331) is as follows: when the deformation data collected by the flexible optical fiber sensing strip (22) is lower than the first threshold, it is determined that the vehicle is bending normally; when the deformation data exceeds the first threshold and the resistance of the conductive monitoring coating (21) does not change characteristically, it is determined that the wire harness is abnormally squeezed; when the deformation data exceeds the second threshold and the resistance changes accordingly, it is determined that the insulation layer has failed.

8. The automotive low-voltage wiring harness insulation failure early warning structure based on conductive coating and fiber optic sensing according to claim 1, characterized in that: The three-level warning signals output by the signal processing and warning module (331) are as follows: Level 1 warning corresponds to slight aging and minor wear of the insulation layer, which is only indicated by text on the vehicle instrument panel; Level 2 warning corresponds to local cracking and moisture, which triggers an audible and visual alarm and prompts the driver to have the vehicle repaired as soon as possible. A Level 3 warning corresponds to severe damage and short circuit risk, and simultaneously sends a signal to the vehicle-mounted VCU to activate a graded power-off protection mechanism.

9. The automotive low-voltage wiring harness insulation failure early warning structure based on conductive coating and fiber optic sensing according to claim 1, characterized in that: The optical signal demodulation unit (321) accurately locates the specific interval of insulation failure by identifying the characteristic wavelength offset of the fiber optic grating sensing unit (322) at different positions, combined with the spiral winding pitch of the flexible fiber optic sensing strip (22) and the grating layout spacing, with a positioning accuracy of ≤15cm.

10. The automotive low-voltage wiring harness insulation failure early warning structure based on conductive coating and fiber optic sensing according to claim 1, characterized in that: The end connector (16) adopts a modular plug-in structure. The warning mechanism is integrated inside the end connector (16). The signal processing and warning module (331) transmits the warning level, fault location and insulation health data to the vehicle VCU and cloud platform in real time, realizing online monitoring and remote operation and maintenance management of the entire life cycle of the wiring harness.

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