Design Principle of Vehicle Harness

(A) power distribution design
    Whether the design of the power supply system of the automobile is reasonable is directly related to the normal operation of the automobile electrical parts and the safety of the whole car. Therefore, the starting point of the automobile harness design in the world is basically based on safety. The vehicle electrical system consists essentially of three parts.
    Battery direct power supply system (commonly known as constant power or 30 electricity). This part of the power supply load is generally the car's safety parts or important parts, the main purpose is to provide energy for these pieces as little as possible to control, to ensure that these pieces can not start even if the car can work for a short time to facilitate To the site maintenance and so on. Such as: engine ECU and engine sensor power supply, fuel pump power supply, ABS controller power supply, diagnostic interface power supply.
    Ignition switch control of the power supply system (commonly known as IG file or smart). This part of the electrical device is basically in the case of engine operation and operation only, from the generator power supply, to avoid charging the battery when the power of the possibility of charging. Such as: instrument power, brake light power, airbag power and so on.
    The load is unloaded when the engine is started (commonly known as ACC power). This part of the electrical parts of the general load is relatively large, and the car does not have to start working. Generally have cigarette lighter power, air conditioning power, Shoufang Ji power, wiper power and so on.
   (B) fuselage should have a clear sign, when its fuse, its logo should still exist in order to facilitate the replacement. The fusible characteristics of fusible lines are shown in Table 1.

(C) the selection of the relay design
    The relay is divided into two kinds of current and voltage. Generally according to the electrical power and the carrying capacity of the switch to decide whether to use the relay. Commonly used relay equipment generally have wipers, speakers, defrost, headlamps, fog lights, fans, blowers, turn lights (flashers) and so on. Relay 6V, 12V, 24V3 kinds of commonly used relay rated voltage of 12V.
    Selection of relays to refer to the technical requirements:
    ① good reliability;
    ② stable performance;
    ③ light weight, small size, long life, the impact of small components around;
   ④ simple structure, good process, low cost.
   (4) the principle of allocation of iron distribution
    Engine ECU, ABS and other vehicle performance and safety impact, and vulnerable to interference with other electrical equipment, so these pieces of the ground must be set alone. For the airbag system, its ground point should not only be set alone, and in order to ensure its safe and reliable, it is best to use double ground. Its purpose is one of the ground failure, the system can pass through another ground to ensure that the system safe work. Radio systems to avoid interference, but also a separate ground.
    Weak signal sensor of the ground is best independent, take the point is best from the sensor closer to the location to ensure the true transmission of the signal. Other electrical devices can be combined with each other according to the specific layout of the common points. The principle is close to the ground, to avoid the cable is too long, resulting in unnecessary voltage drop.
    In order to increase the safety, the engine, the body generally to the battery alone connected to the battery negative ground; take the iron, and so on. Way: First, through the hole connector grounding, this method must be in the tail of the joints baked heat shrink tube insulation; Second, through the internal short jacket directly to the ground.

Key words: automobile harness harness design