The new four modernizations also put forward more stringent requirements for the development of automobile wiring harness technology. High pressure and light weight is the irreversible development trend of automobile wiring harness industry. High voltage of electrical equipment can reduce the rated current, so thinner high voltage wire can be used to reduce the weight of wiring harness. The fuel consumption per 100 km can be reduced by 0.3-0.6L for each 100kg reduction of the vehicle, or the range can be increased by 10%-11%. Car wiring harnesses can improve mileage by 2% if they can lose 20kg in weight. The following is a brief talk about the development trend of automobile wiring harness.

1. Lightweight

A) Lightweight wiring harness system design

The use of reasonable electrical structure and electrical system layout, wiring, and reasonable insurance within the range of safety, conductor selection and matching is the key to design lightweight. Pictured above is the old Mercedes-Benz GL and below is the Tesla Model 3. The previous generation of the architecture of BenzGL adopts a distributed functional architecture, that is, each function is integrated in each ECU module. There are 70 to 80 modules, and there are hundreds of modules. Although the modules are all network communication, the weight of the vehicle wiring harness is as high as 40-50kg, and the weight of the vehicle wiring harness is as high as 25-30kg. Tesla adopts a domain controller combined with integrated distribution, including central computing module (CCM), left body control module (BCM_LH) and right body control module (BCM_RH). Many functions are integrated in the domain controller, leaving only the ECU responsible for peripherals to be distributed. The domain controller is bridged by CAN or Ethernet bus, and the overall vehicle wiring harness weight is only 20kg, with a total length of 1.5km. It has better electricity saving effect.

For example, the front SAM is arranged on the right side of pillar A, and the front cabin, ceiling, instrument and body line can be connected to directly connect the corresponding plug-in position on SAM, reducing the use of inline, and also reducing some weight.

B) Lightweight of wire harness material:

Wire lightweight

Conductor selection is more reasonable, such as 0.13 mm2 conductor or soft line, can reduce weight and save space. The replacement of conventional thin-walled wires, such as 0.13mm2 ultra-thin-walled PVC wires, can achieve a 13% weight reduction and a 24% size reduction. The application of aluminum conductor, compared with copper conductor, can reduce the total weight of the body harness by more than 30%. High voltage aluminum conductor using aluminum alloy conductor is 46-49% lighter than copper conductor.

Connector Lightweight

One of the effective ways to reduce the weight of the wiring harness is to reduce the volume and weight of the connector. Currently, small connectors developed by Sumitomo, a Japanese company, weigh 20 to 40 percent less for the same function. Take Rosenberg HFM as an example, Rosenberg changed the traditional Fakra into the HFM (High-speed Fakra Mini) series with compact structure, smaller size and faster transmission speed.

Foaming technology is used for plate support and other products

Polyurethane foaming technology can also effectively reduce the weight of the wiring harness, but also facilitate the spatial arrangement of the wiring harness. It has the characteristics of light weight, short forming cycle, reducing warpage and improving accuracy, strong ability to resist oil and dust, and no noise after installation.

2. Modularization and integration of wiring harness system

When the wiring harness is modular designed, the wiring harness is divided into small module wiring harness according to the function. In production, different functional modules can be selected for assembly according to the functional requirements of the configuration. For example, Benz divides automobile wiring harness into each small module wiring harness according to its function, and then selects different modules for assembly according to different configuration requirements. However, a large part number will not be produced, and all selected wiring harness module numbers will be printed on the product label. The whole vehicle harness adopts KSK modular production mode, which can meet the different needs of customers to the greatest extent.

The wiring harness system is also integrated with other modules, such as door module, ceiling module, front and rear protection module, so as to reduce the assembly time of the vehicle in the production process and improve work efficiency.

The number of combinations and complexity of wiring harness parts is determined by how many options are available on the vehicle's configuration sheet. Take a C-class car as an example, the whole system can realize more than 100 optional assembly combinations. As a result, the wiring harness BOM becomes more complex and the number of combinations explodes. Although the adoption of modular production mode has been eased, but still increased a lot of management costs.

In this form, the wiring harness is a new development trend. For example, Tesla has started the design of hardware separation between soft and hard. The mass production vehicle is directly the unified hardware, and then the actual function, upgrade, expansion, optimization and so on are given to the hardware through OTA. As a component of software 0, the wiring harness can directly cover the largest range of electrical components under the trend of separation of hard and soft, breaking free from more than 100 configuration combinations.

3. Redundancy design of wiring harness system

With the rapid development of L3L4 automatic driving technology, the automatic driving function has put forward the functional safety design requirements for some key parts (ESP, EPS, etc.), that is, redundant design. Redundancy design puts forward new requirements for the design of power supply system, power distribution system and circuit system. At present, some schemes directly add a set of power supply and power distribution system, intelligent circuit breaker to meet the requirements of functional safety level D. Some schemes add intelligent power distribution system, which needs to be combined with the actual state of the vehicle to choose a reasonable scheme.

4. High-speed communication

With the development of intelligence, network, V2X, ADAS, automatic driving field development, the data acquisition and processing speed requirements are more and more high, vehicle network system, also from the original CANLIN development to CANFD, 100 MB Ethernet (100M), Gigabit Ethernet (1000M). The wiring harness system should also be upgraded accordingly. Although CAN twisted-pair and 100Mb Ethernet twisted-pair look the same in appearance, but are substantially different in nature, 100BASE-T1 Ethernet wiring harness defines characteristic parameters such as characteristic impedance, plug loss and return loss in detail, and also specifies the number of inlines in the middle.