Industry knowledge

The function of car's wire harness

In modern automobile, there are many automobile harnesses, and the electronic control system is closely related to the harness. Someone once made a vivid analogy: if the functions of microcomputer, sensor and actuator are compared with human body, it can be said that microcomputer is equivalent to human brain, sensor is equivalent to sensory organ, and actuator is equivalent to motor organ, then the harness is nerve and blood vessel.

Wire harness is the main network of automobile circuit. It connects the electrical and electronic components of automobile and makes them function. Without harness, there will be no automobile circuit. At present, whether it is an advanced luxury car or an economical ordinary car, the wiring harness is basically in the same form, which is composed of wires, connectors and wrapping tape. It should not only ensure the transmission of electrical signals, but also ensure the reliability of the connecting circuit, supply the specified current value to the electronic and electrical components, and prevent electromagnetic interference to the surrounding circuits, And eliminate the electrical short circuit.

In terms of function, there are two kinds of wires harness: the power line carrying the power of the driving actuator (actuator) and the signal line transmitting the input command of the sensor. The power line is a thick wire that carries large current, while the signal line is a thin wire that does not carry power (optical fiber communication); For example, the cross-sectional area of wires for signal circuits is 0.3 and 0.5mm2.

The cross-sectional areas of wires for motors and actuators are 0.85 and 1.25mm2, while the cross-sectional areas of wires for power circuits are 2, 3 and 5mm2; Special circuits (starter, alternator, engine grounding wire, etc.) have different specifications of 8, 10, 15 and 20mm2. The larger the cross-sectional area of the conductor, the greater the current capacity. In addition to considering the electrical performance, the selection of wires is also restricted by the physical performance when on-board, so its selection range is very wide. For example, the frequently opened / closed door on a taxi and the wire across the body should be composed of wires with good flexural performance. The conductor used in high temperature parts generally adopts the conductor coated with vinyl chloride and polyethylene with good insulation and heat resistance. In recent years, the use of electromagnetic shielding wires in weak signal circuits is also increasing.

With the increase of automobile functions and the universal application of electronic control technology, there are more and more electrical parts and wires. The number of circuits and power consumption on the automobile increase significantly, and the harness becomes thicker and heavier. This is a big problem to be solved. How to make a large number of wire harnesses in the limited automobile space, how to arrange them more effectively and reasonably, and how to make the automobile wire harness play a greater role has become a problem faced by the automobile manufacturing industry.