Protective materials The exterior of the automobile engine wiring harness is generally covered with protective materials such as corrugated pipes, PVC pipes, heat shrinkable tubes, tapes, etc. for basic wrapping protection, and buckles, cable ties, brackets, etc. Each protective material has its own characteristics and functions. To realize the circuit protection design, it is necessary to understand and correctly apply various protective materials in combination with the actual wiring harness application environment.
The most widely used protective material for engine wiring harness is bellows, which is sleeved on the outside of the wiring harness to protect the wiring harness from being cut. In the corrugated tube, the wire harness filling rate should be kept at about 60%. Too dense wire harness will cause the wire harness to wear inside the corrugated tube. Ordinary bellows generally have a long-term working temperature of -40~120 °C, and a short-term maximum of 150 °C. The flame retardant grade is UL94-HB, which can withstand the harsh environment of high temperature and high vibration on the engine.
When the wire harness must be routed from a location with a high heat radiation temperature, the outside of the corrugated tube can be wrapped with thermal insulation material to prevent the corrugated tube from being baked. The closed corrugated pipe currently used has better protection effect and more beautiful appearance.
At present, the automobile engine is developing into a compact type. After all, the bendability of the bellows is limited, and the wiring requirements cannot be achieved in some narrow spaces of the engine. Therefore, these parts need to be replaced by PVC pipes. The main component of PVC pipe is polyvinyl chloride, and its basic protection function is similar to that of corrugated pipe, but because of its soft texture, it has better flexibility and bending performance, but its high temperature resistance is not as good as that of corrugated pipe. Folding requires a high position.