Introduction to key technologies in automotive wiring harness design

----Key technologies of wiring harness design----

1. Overview

The wiring harness is a wiring component that connects various electrical devices in the automobile circuit. It is composed of an insulating sheath, a terminal, a wire, and an insulating wrapping material. The automobile wiring harness is the network carrier of the automobile circuit and the blood vessels and nervous system of the electrical components of the whole vehicle. Without the wiring harness, there would be no automobile circuit. With the increase of the whole vehicle's electronic and electrical systems, the electrification, intelligence, networking, sharing of vehicles and the application of 5G technology, the quality and volume of the wiring harness have increased dramatically, further increasing the difficulty of wiring harness layout.

The wiring harness plays a vital role in the realization of the electrical and electronic functions of the whole vehicle. The automotive wiring harness is mainly used to connect the battery, distribution box, actuator, controller, sensor, power battery and other components of the vehicle, provide power and signal transmission for the electrical and electronic components of the whole vehicle, and provide basic connection for the control circuit to realize all electrical functions. Electrical safety and signal accuracy have extremely high requirements for the connection stability of the wiring harness to ensure that the line does not produce overload, short circuit, open circuit, voltage fluctuation and signal transmission attenuation. In the overall design of the wiring harness layout, it is necessary to fully consider the relevant boundary conditions, the body, powertrain, instrument panel, chassis, and interior parts must be fully and systematically understood, and the possible impact of each related part on the wiring harness layout must be fully considered, and corresponding reasonable requirements for the design of related parts must be put forward. At the same time, we must fully consider the temperature distribution and vibration of the whole vehicle, avoid the wiring harness passing through the high temperature area, and avoid the wiring harness from vigorous vibration, so as to improve the reliability of the wiring harness layout.

2. Several basic trends in vehicle wiring harness layout design

In the layout of the wiring harness of traditional models, there are usually many types of layouts such as H, L, E, and R. The most representative ones are H type and E type, as shown in the figure below.

Figure 1. Wiring arrangement of H type (left) and E type (right)

New energy vehicle models usually adopt a Sichuan-type layout in the wiring harness layout, as shown in the figure below, that is, the high-voltage wiring harness is in the center and the low-voltage wiring harness is distributed on both sides, avoiding EMC problems caused by the high and low voltage wiring harness layout.

Figure Wire harness layout Sichuan type

3. Basic classification of vehicle wiring harness

In the wiring harness of the whole vehicle, we can divide the wiring harness according to area and function into: front cabin wiring harness assembly, front bumper wiring harness assembly, instrument panel wiring harness assembly, ceiling wiring harness assembly, battery positive wiring harness assembly, battery negative wiring harness assembly, floor wiring harness assembly, engine wiring harness assembly, transmission wiring harness assembly, left front door wiring harness assembly, right front door wiring harness assembly, rear door wiring harness assembly, tailgate wiring harness assembly, trunk wiring harness assembly and high-voltage wiring harness, etc.

4.Confirmation of wiring harness layout

The division of the wiring harness is closely related to the structure and assembly process of the vehicle, so it is not necessary to stick to the above division forms. Strive to achieve simple structure, convenient disassembly and assembly, beautiful layout, and good fixation and protection. At the same time, modular design should be used in the wiring harness to reduce loops. In addition, in the design of the wiring harness, local wiring harnesses need to adopt adapters, etc., which depends on the specific vehicle model. The direction, vias, fixation, temperature vibration, etc. of the wiring harness should be fully considered, and all possible situations should be considered as far as possible in the early stage of design to avoid subversive errors in the future. Clarify the input and output information. Solve all major problems that may arise in the future.

After fully analyzing all the above information, the overall layout of the wiring harness is carried out. The wiring harness structure is required to be simple and easy to manufacture, assemble and maintain. The main electrical components are preliminarily connected, and the approximate wiring harness division method is determined. After the plan is formed, the feasibility analysis of the wiring harness layout plan is carried out to confirm the direction type and segmentation information of the vehicle wiring harness.