The automobile wiring harness is the network main body of the automobile circuit. Without the wiring harness, there would be no automobile circuit. At present, whether it is a high-end luxury car or an economical ordinary car, the form of the wiring harness is the same, and it is composed of wires, connectors, and wrapping tape.
After understanding the basic concepts, Qifei Automotive Design comprehensively analyzed the wire harness design from the perspective of the wire harness design process, principles, job requirements, and development prospects.
Automotive wiring harness design
Design of automobile wiring harness
The function of the wire harness in the entire vehicle is to transmit or exchange the power signal or data signal of the electrical system to realize the functions and requirements of the electrical system.
The electrical layout engineer provides the functions, electrical loads, and related special requirements of the vehicle’s electrical system. The status of electrical components, installation location, and the form of connection between the wiring harness and electrical components.
According to the electrical functions and requirements, draw the electrical schematic diagram and circuit diagram of the vehicle.
The energy distribution is carried out for each electrical subsystem and loop according to the electrical principle circle, including the distribution of power supply ground wires and grounding points.
According to the distribution of electrical components in each subsystem, determine the wiring form of the wire harness, the electrical components connected to each wire harness and its direction on the car; determine the external protection form of the wire harness and the protection of the through holes; determine the fuse or circuit breaker according to the electrical load device; then determine the wire diameter of the wire based on the number of fuses or circuit breakers; determine the wire color of the wire based on the function of the electrical device and relevant standards; determine the terminals and sheaths on the wire harness that are connected to it based on the connector of the electrical device itself. model.
Draw two-dimensional wire harness diagrams and three-dimensional wire harness layout diagrams.
According to the approved three-dimensional wire harness layout drawing, the two-dimensional wire harness diagram is checked. The two-dimensional wire harness diagram can only be issued if it is accurate. After approval, trial production and production will be carried out.
Two-dimensional key points of automotive wiring harness design
Key points of two-dimensional wiring harness diagram design
1.1 Power distribution box
The power distribution box (fuse and relay) is the core of the vehicle’s electrical system. It plays a role in distributing loads, centralizing power supply, saving space, simplifying wiring harnesses, reducing costs, and facilitating maintenance. Generally, it can be designed into 2 to 3 according to needs.
1.2 Selection of wires
The selection of wire colors is based on the Colors of Low-Voltage Wires for Automobiles.
The ambient temperature around the engine is high and there are many corrosive gases and liquids. Therefore, be sure to use high-temperature-resistant, oil-resistant, vibration-resistant, and friction-resistant wires.
The wires on the trunk lid must maintain their elasticity at low temperatures, so cold elastic wires must be used to ensure their normal operation.
(4) The wires on the automatic transmission must be resistant to high temperatures and hydraulic oil, and their temperature stability must be good.
Weak signal sensors should use shielded wires, such as sensors in the EFI system, CAN loops, wheel speed sensors in ABS; SPEAKER loops in radios, related sensors in airbags (such as collision sensors), etc.
The door’s inner wire has high bending resistance requirements.
1.3 Selection of connectors
The selection of plug connectors should ensure good contact with electrical components to minimize contact resistance and improve reliability.
Reasonably select the connector according to the cross-sectional area of the wire and the size of the passing current.
For the sheaths connected in the engine compartment, waterproof sheaths must be selected because the temperature and humidity in the cabin are relatively high and there are many corrosive gases and liquids. If the same sheath is used in the same wire harness, its color must be different.
To reduce the type and quantity of sheaths used for wire harness docking, hybrid parts are preferred to facilitate assembly and fixation. For terminal connectors for airbags, ABS, ECU, etc. that require higher performance, it is best to use gold-plated parts to ensure safety and reliability.