Outline of Precautions for Automotive Wiring Harness Arrangement

With the continuous improvement of safety, comfort and environmental protection requirements of modern automobiles, the number of circuits and power consumption on automobiles have increased significantly, so how to arrange a large number of wiring harnesses more effectively and reasonably in the limited automotive space has become a problem faced by the automotive industry. This paper focuses on the layout of automotive wiring harness, and briefly introduces the matters needing attention in the layout of automotive wiring harness. 1. The harness fixing points shall be arranged reasonably and fixed reliably (1) According to the actual installation position of the harness on the vehicle, in order to avoid the drooping and displacement of the harness, considering the weight of the harness, the fixing method and the convenience of the fixing position, the harness must be fixed with sufficient and reasonable fixing points and fixing methods. (2) Set the fixed points according to the direction of the harness and the specific shape of the vehicle body. The distance between two fixed points on the straight line without fulcrum is generally not more than 300 mm. One fixed point can be arranged at the obtuse angle inflection point. Two fixed points should be arranged at the right-angle inflection point. The acute angle inflection point should be avoided in the harness. (3) Select the type and size of the fixed buckle according to the shape and outer diameter of the harness, and meet the requirement of bearing the weight of the harness. (4) At the position of the connector connected with other harnesses and electrical devices, a fixing point shall be set at a suitable position not more than 120mm in front of the connector. (5) It is considered to set a fixed point on the main line at the fulcrum position, and the distance between the fixed point and the fulcrum shall not be greater than 100mm. (6) In the installation direction of the fixed buckle, there must be enough space to facilitate the installation and disassembly of the buckle. 2. The appearance is neat and the harness is arranged in bundles (1) The harness should be arranged along the edge and along the groove (the wiring groove designed on the car body) to avoid direct pressure on the harness. The harness shall not be exposed in the cab; the position where the harness can be observed, such as the engine room, shall be set with eye-catching attraction points or eye-catching colors, and the harness installed here shall not be prominent or conspicuous. (2) In the direction of projection, the arrangement shall be arranged in a horizontal and vertical chessboard pattern to avoid oblique line arrangement. (3) The clearance with the pipeline shall be uniform, and the clearance with the surrounding parts shall be reasonable.

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3. Avoid interference between the harness and the surrounding parts (1) Do not directly contact with the sharp edge of the vehicle body. First, leave a gap. Second, increase protection to avoid the sharp edge of the vehicle body damaging the external insulation layer of the harness, resulting in short circuit accidents; (2) When installed on vibrating or moving parts, the length shall be reserved according to the actual situation. The reserved length is determined according to the vibration amplitude of the component and the maximum movement stroke of the moving part. Ensure that the reserved length can prevent the vibration from being transmitted on the wire harness and the wire harness from bearing tension. If the harness is subjected to vibration transmission or tension for a long time, it may cause virtual connection between the internal contact/connector terminals of the harness. For example, the connection between the engine harness and the engine compartment harness. (3) The clearance with the moving parts shall be greater than 25mm, such as the clearance between the wire of the wiper motor and the connecting rod. (4) The distance from the exhaust manifold shall be more than 50mm. (5) The distance from the parts with temperature higher than 150 ℃ at the engine shall be more than 50mm. (6) Do not use the same fixing point as the fuel pipeline and brake pipeline. (7) Do not cross or contact with fuel pipeline and brake pipeline. Especially in the wiring harness connection and oil circuit connection, avoid the fire caused by the damage and short circuit of the circuit surface and the evaporation density of the oil when the conditions reach certain conditions. 4. Anti-electromagnetic interference (1) The sound harness must have anti-electromagnetic interference measures to ensure the signal-to-noise ratio of the sound system and other acquisition signals, so that it can work normally. (2) The signal line of engine control module, instrument signal line, ABS signal line and airbag signal line must be provided with anti-electromagnetic interference measures (such as twisted pair, shielded wire, etc.) to ensure the normal operation of each system. (3) Avoid the electromagnetic interference source of parts, for example, arrange some signal lines as far away from the interference source as possible, such as electric horn, ignition coil, motor and other electrical appliances. (4) The signal power line of the sensor shall be kept away from the power line of the high-current parts, and the interval shall be greater than 300 mm to avoid signal interference. (5) Reasonably arrange the electrical appliances and shorten the length of the signal line. (6) Grounding wires of some key systems and important systems shall be separately arranged at the same position to avoid interference from other grounding wires. For example, the airbag system, ABS, ECU engine control system and audio system are all two-wire systems, and the whole system adopts one grounding point. (7) Add shielding grounding on the shell of the electrical appliance at the position vulnerable to interference.

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