The wiring design of a vehicle wiring harness must balance electromagnetic compatibility (EMC) and mechanical reliability. Scientifically planned wiring paths, optimized shielding structures, and enhanced protective measures are essential to effectively avoid signal interference and mechanical wear, ensuring the stable operation of the vehicle's electronic systems. This process involves the integration of multiple technologies, including electromagnetic field control, mechanical stress dispersion, and environmental adaptability enhancement, and is one of the core challenges in vehicle wiring harness design.
Properly planning wiring paths is the primary strategy to avoid signal interference. Strong electromagnetic sources exist inside vehicles, such as motors, inverters, and on-board chargers. The electromagnetic fields generated during their operation may interfere with sensitive signals through spatial coupling or conduction. During wiring design, high-voltage power harnesses and low-voltage signal harnesses should be arranged in layers, maintaining sufficient spacing to reduce electromagnetic coupling. For example, power harnesses should be fixed along the vehicle frame, away from areas with concentrated signals such as the instrument panel and sensors. Simultaneously, long parallel runs of power and signal harnesses should be avoided; when necessary, a perpendicular crossing design should be used to reduce mutual inductance. Furthermore, signal harnesses of different frequency bands need to be arranged separately. High-frequency signals (such as cameras and radar) should be kept away from low-frequency interference sources, while low-frequency signals (such as switch control) should avoid sharing paths with high-current lines.
Optimizing the shielding layer and twisted-pair structure is a key means of suppressing signal interference. For sensitive signals susceptible to interference, such as CAN bus, LIN bus, and Ethernet, a shielded twisted-pair design is required. The shielding layer can block the intrusion of external electromagnetic fields, while the twisted-pair structure cancels out some interference through its own mutual inductance. The design must ensure that the shielding layer is continuous without breaks and that a 360-degree loop is achieved at the connector to avoid shielding failure. For example, in the battery management system (BMS) of new energy vehicles, shielded twisted-pair cables can effectively prevent high-voltage power harnesses from interfering with temperature sensor signals, ensuring data acquisition accuracy. In addition, for high-frequency signals, coaxial cables or shielded twisted-pair cables can be used to further improve anti-interference capabilities.
Prevention of mechanical wear requires addressing both harness fixation and motion compensation. During vehicle operation, the harness will experience stretching, bending, or friction due to vehicle vibration, hinge movement, and temperature changes. During the design phase, it's essential to establish fixing points in critical locations, such as the engine compartment, door hinges, and under seats, using clips, cable ties, or cable channels to securely hold the wiring harness in place, preventing direct contact between the harness and metal components. Simultaneously, for wiring harnesses near moving parts (such as doors and steering columns), extendable corrugated tubing or spiral sheaths should be used, allowing sufficient slack to prevent breakage due to excessive stretching. For example, door wiring harnesses should be designed with "S" or "U" shaped bends, combined with wear-resistant sheath materials, ensuring the harness remains undamaged during long-term opening and closing.
Environmental adaptability design is another key aspect of reducing mechanical wear. Vehicle wiring harnesses may be exposed to harsh environments such as high temperatures, low temperatures, humidity, and salt spray. Therefore, it's crucial to select sheath materials with strong weather resistance, such as polyvinyl chloride (PVC), cross-linked polyethylene (XLPE), or thermoplastic elastomers (TPE). These materials must possess UV resistance, oil resistance, and chemical corrosion resistance to prevent sheath cracking or insulation aging caused by environmental erosion. Furthermore, in areas prone to contact with mud and water, such as the chassis or wheel arches, the wiring harness must use waterproof connectors and sealing plugs to prevent moisture intrusion that could lead to short circuits or corrosion.
The reliability design of connectors and terminals directly affects the stability of signal transmission and mechanical connections. Connectors must possess high insertion and extraction force, low contact resistance, and vibration resistance to prevent poor contact due to vehicle vibration. Connectors with locking mechanisms should be selected during the design phase to ensure they do not loosen after insertion; simultaneously, terminals should be tin-plated or gold-plated to improve oxidation resistance and reduce signal attenuation caused by contact surface oxidation. For example, in the high-temperature environment of the engine compartment, high-temperature resistant connectors must be selected to prevent sealing failure due to material deformation.
Finally, the rationality of the wiring design is verified through simulation and testing. During the design phase, electromagnetic compatibility (EMC) simulation software can be used to simulate the electromagnetic field distribution of the wiring harness, optimizing the wiring path and shielding structure; mechanical stress analysis is used to evaluate the fatigue life of the wiring harness under vibration, bending, and other conditions. During the prototype stage, real vehicle testing is required, including electromagnetic interference testing, mechanical vibration testing, and environmental adaptability testing, to ensure that the wiring harness can still work stably under complex working conditions.
