Wire Harness Processing Basic Knowledge Manual
Definition: The wiring harness is an indispensable system-level component in the vehicle. Its function is to provide and distribute power to various systems of the vehicle, and at the same time act as a medium for signal transmission between various components.
1. Applicable standards
wire
National Standard
The characteristics of national standard wires are thick insulation, relatively soft and good ductility.
GB / T8139 , JB/T8139 , QC/T730 , QC/T1037
Japanese Standard
The Japanese standard conductor is characterized by thin insulation and good flexibility.
JASO_D608 , JASO_D609 , JASO_D611 , JISC_3406
German Standard
German standard wire insulation is thinner and more flexible
DIN_72550 , DIN72551 , DIN_76772 , VW_60306 , LV_112-3
American Standard
The insulation of American standard wires is generally thermoplastic or thermosetting elastomer, and there are also irradiated wires.
SAE_J1128 , SAE_J1678 , USCAR-21
2. Classification
2.1 Ordinary twisted pair wire
Basic concept: twisted pair cable is made of two ordinary thin wires with insulation layer twisted together in a certain proportion.
Principle: If the interference generated by the external electromagnetic signal on the two wires is equal in magnitude and opposite in phase, the interference signal will cancel each other out. Twisted pair is the simplest way to eliminate interference. In some cases where the requirements are not very strict, twisted pair can be used.
2.2 Shielded wire
2.2.1 Classification
Aluminum foil shielded cable Aluminum foil is mainly used to shield high-frequency electromagnetic waves, preventing high-frequency electromagnetic waves from contacting the network cable conductor and generating induced current, increasing crosstalk.
Braided shielding wire Braided shielding wire is generally made of tinned round copper wire. It is mainly used to prevent low-frequency electromagnetic interference. Its working principle is the same as that of aluminum foil.
2.2.2 Working Principle Taking aluminum foil shielded cable as an example, when high-frequency electromagnetic waves come into contact with aluminum foil, according to Faraday's law of electromagnetic induction, the electromagnetic waves will tend to attach to the surface of the aluminum foil and generate induced current. At this time, a conductor is needed to conduct the induced current into the ground to prevent the induced current from interfering with the transmitted signal. (Therefore, shielded cables generally require that one end of the shielding layer be grounded and the other end be suspended.)
The black wire in the aluminum foil shielded cable is the grounding wire, and the braided mesh in the braided mesh shielded cable is the grounding wire. Aluminum foil shielded cables are generally used now because their wiring harness processing is relatively simple.
2.2.3 Advantages Shielding is the most effective measure to avoid electromagnetic interference, because the external interference electromagnetic waves will not pass through when encountering metal materials during the propagation process, but will be forced to change direction and move along the metal. Therefore, if the metal material is wrapped around the outside of the device or wire to be shielded for shielding, and connected to the earth through the grounding wire, the interference electromagnetic waves will flow to the earth through the grounding wire, and the signal in the shielded wire can be transmitted normally.
Heling Industrial Wiring Harness is an innovative enterprise focusing on the design and manufacture of connectors and wiring harness solutions. Its main products are divided into wiring harnesses: industrial circular wiring harnesses, industrial network cables, industrial buses, servo wiring harnesses; cables: industrial buses, industrial network cables, drag chain cables; connectors: industrial circular connectors, rectangular connectors.
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