Wiring Harness provides a total of service equipment for a certain load source group, such as trunk roads, switching devices, control systems, etc. The basic research content of traffic theory is to study the relationship between traffic volume, call loss and harness capacity. Wiring harness is an important basic concept in the theory of traffic.
A load source is a service object of a harness, usually a user device; In a broad sense, a first-level device is the load source for the next level of equipment. In telephone communication, the load source is also called the source, the number of service devices contained in the harness, called the harness capacity, fig. 1 is a schematic diagram of the wiring harness. The harness's capacity is V, which provides services for n load sources. Any load source that makes a call can occupy one of the idle service devices in the harness.
The requirements of the automotive wiring harness for materials are also very stringent:
Including its electrical properties, material distribution, temperature resistance, and so on, are higher than the general requirements of wiring harness, especially related to the safety requirements more stringent.
1, the engine ambient temperature is high, corrosive gases and liquids are also more, therefore, the engine wiring harness must be used to withstand high-temperature, oil, vibration resistance, friction-resistant wire.
2. The wire used in the automatic transmission is resistant to hydraulic oil, high temperature and good temperature stability.
3. The wire harness on the trunk cover should keep its elasticity at low temperature, so the cold elastic conductor should be used to ensure its normal work.
4, weak signal sensor to use shielded wire.
5, ABS harness assembly to use 150-200 ℃ high-temperature, external protection insulation layer hard, wear-resistant, but the wire core to be more than 133 root stranded wire.
6, power line, such as starter alternator output line of the battery wire used to withstand large current insulation layer heat dissipation performance, voltage reduction of the special wire.
In modern automobiles, the electronic control system is closely related to the wiring harness. Someone once played a figurative analogy: the computer is equivalent to the human brain, the sensor is equivalent to the sensory organs, the executive component is equivalent to the motor tube, then the wiring harness is nerves and blood vessels.
The automobile wiring harness is divided from function, there are two kinds of lines which carry the power line of the driving actuating element (actuator) and the transmission sensor input instruction. A power line is a thick wire that transports large currents, while a signal line is a fine wire (optical fiber communication) that does not carry electricity.
The Traverse area of the electric motor and the executing component is 0.85, 1.25mm2, and the power circuit with wire cross-section area of 2, 3, 5mm2, and special circuit (starter, alternator, engine grounding line, etc.) are 8, 10, 15, 20mm2 different specifications. The choice of wire, in addition to considering electrical properties, but also by the vehicle when physical performance constraints. For example, the frequent open/closed doors on a taxi and the wires across the body should consist of a conductor of good flex. In recent years, the electromagnetic shielding lines used in weak signal circuits have also been increasing.
With the increase of automobile function, the universal application of electronic control technology, the number of circuits on the car and the power consumption significantly increased, the wiring harness becomes heavier, how to make a large number of wiring harness in the limited space of the car more effective and reasonable layout, so that the car harness to play a larger function, has become the problem of automobile manufacturing industry.
Selection of wire harness materials
The quality of harness material directly affects the mass of wiring harness, the selection of wire harness material, and the quality and service life of wiring harness. To remind you that the choice of online harness products, must not covet cheap, cheap wiring harness products may be used is inferior wiring harness material. How to distinguish the quality of wiring harness? Understand the material of wiring harness. The following is a material for wiring harness selection.
Wire harness is usually composed of wire, insulating sheath, terminal and wrapping material. As long as you know the material, you can easily tell the good or bad of the wiring harness.
I. Material selection of terminals
The copper used in the terminal material (copper) is mainly brass and bronze (the hardness of brass is slightly lower than that of bronze), in which brass occupies a larger proportion. In addition, different coatings can be selected according to different requirements.
II. Selection of insulating sheath
Sheath material (plastic parts) commonly used materials include PA6, PA66, ABS, PBT, pp and so on. In accordance with the actual situation in the plastic add flame-retardant or reinforcement materials to achieve enhanced or flame-retardant purposes, such as the addition of glass fiber reinforced.
III. Selection of wire harness
According to the different use of the environment, select the appropriate wire material.
IV. Selection of dressing materials
Wiring harness to wear-resistant, flame-retardant, anti-corrosion, prevent interference, reduce noise, beautify the appearance of the role, generally according to the working environment and the size of the space to choose the dressing material. In the dressing material's choice usually has the belt, the corrugated pipe, the PVC tube and so on.
Previous: Wire Harness Common Fault Analysis