How do automotive wiring harnesses withstand high temperatures through multiple protective designs?
Publish Time: 2025-08-27
The automotive wiring harness, the "neural network" of the vehicle's electrical system, runs through the engine compartment, chassis, cab, and body. Some wiring harnesses are exposed to high temperatures for extended periods of time, such as near heat sources like the engine, exhaust pipe, turbocharger, or battery. Sustained high temperatures can cause insulation to age, become brittle, and crack, potentially leading to serious safety hazards such as short circuits and fires. Automotive wiring harnesses must feature multi-layered protection to ensure stable and safe operation even in extreme temperatures.1. Selecting high-temperature-resistant materials is fundamental.The protection of automotive wiring harnesses begins with the material itself. Wire insulation is commonly made of specialized, high-temperature-resistant materials, such as cross-linked polyethylene (XLPE), high-temperature modified polyvinyl chloride (PVC), polyolefins (TPX), fluoroplastics (FEP, ETFE), or silicone rubber. These materials maintain excellent insulation, mechanical strength, and flexibility even at high temperatures. For example, FEP can withstand temperatures exceeding 200°C and is often used in critical wiring within the engine compartment. XLPE, through radiation cross-linking, significantly increases its heat distortion temperature and aging resistance, making it widely used in high-voltage wiring harnesses for new energy vehicles.2. Shielding and Jacketing Enhance Thermal StabilityIn high-temperature areas, wiring harnesses are often equipped with additional protective layers. Common options include braided shielding, aluminum foil shielding, or metal bellows. These structures not only provide electromagnetic shielding but also provide some thermal insulation. More specialized high-temperature protection utilizes heat-resistant jackets, such as silicone tubing, braided glass fiber tubing, or asbestos substitutes (such as ceramic fiber). These materials offer extremely low thermal conductivity and excellent temperature resistance (over 300°C), effectively blocking external heat radiation and protecting internal wiring.3. Optimizing Wiring to Avoid High-Temperature Heat SourcesOptimizing layout during the design phase is key to preventing high-temperature damage. Engineers use thermal simulations to analyze the temperature distribution around the engine compartment and power battery, routing the wiring harness in relatively cool areas to avoid direct contact with high-temperature components such as the exhaust pipe and supercharger. At the same time, wiring harnesses should be routed as short and straight as possible to minimize the length of time spent in hot zones. For wiring harnesses that must traverse high-temperature zones, "U-shaped" or "looped" routing is used to allow for expansion space and prevent strain or wear caused by thermal expansion and contraction.4. Use thermal insulation materials for physical isolationIn actual assembly, wiring harnesses are often physically protected using thermal insulation pads, anti-radiation aluminum foil tape, or heat shields. These materials have high reflectivity and low thermal conductivity, effectively reflecting heat radiation and reducing the surface temperature of the wiring harness. For example, applying anti-radiation aluminum foil near the exhaust pipe can reduce the temperature of the adjacent wiring harness by 20–40°C, significantly extending its service life.5. Heat-resistant design of connectors and terminalsThe weak link in wiring harnesses is often the connector. High temperatures can cause deformation of the plastic housing, oxidation of the terminals, or poor contact. Therefore, connectors in high-temperature areas must be made of heat-resistant engineering plastics (such as PA6T, PPA, and LCP) with a temperature rating of over 180°C. Terminal surfaces are typically silver- or tin-plated to enhance conductivity and oxidation resistance, ensuring low contact resistance even at high temperatures.6. Verifying High-Temperature Reliability Through TestingAll wiring harnesses used in high-temperature environments must undergo rigorous durability testing, including high-temperature aging tests (e.g., 125°C for 1000 hours), thermal cycling tests (repeated cycles from -40°C to +150°C), and thermal shock tests to verify compliance with insulation performance, mechanical strength, and electrical stability.Automotive wiring harnesses utilize a multi-faceted system of "high-temperature-resistant materials + protective layers + optimized wiring + thermal insulation measures + heat-resistant connectors + rigorous testing" to create a comprehensive defense against high temperatures. This not only ensures the long-term reliable operation of the vehicle's electrical system but also plays a key role in enhancing overall vehicle safety and durability.
