Analysis and Countermeasures of Automotive EPB Wire Harness Wire Breakage

3 Optimization plan and test automobile wiring harness wire design and selection

It is important to consider the function and environment of the wiring harness. The EPB wire harness is installed in the dynamic bending area of ​​the body chassis and the car parking system determines that the EPB wire harness is a special car wire harness and is a safety part. suggestions below:

3.1 Define the wire type based on the bending resistance requirements, and select bare copper with high grain size and ultra-flexible wires with a large number of core wires to meet the bending life requirements. In order to ensure the strength of the wire, the minimum cross-sectional area of ​​the automotive wire should not be less than 0.5mm2. According to German standard LV112-1, choose ultra-flexible bare copper wire:

3.2 Define the external protective layer and cross-sectional structure of the conductor based on the stress requirements to effectively transmit and divert bending stress; select the structure of the conductor plus a casing to define the wear resistance grade and temperature grade of the material; reasonably set the volume ratio of the conductor in the casing so that the conductor can Stretch and expand within a small range to reduce stress concentration.

3.3 Determine the line length and tolerance based on the force requirements. Generally speaking, the length of each part of the automobile wiring harness is determined based on the actual layout position of the electrical appliances on the body. The actual tolerance should take into account the wiring harness assembly requirements and their dynamic and static conditions. interference issues. Due to the influence of shear force during bending motion, the length should be slightly extra according to the actual length of the line. Generally speaking, the redundancy is between 3% and 5%.

3.4 Define mounting point materials based on stress requirements. Reduce the hardness of the EPB wire harness fixed point material PUR to 75A, eliminate the right-angled edges of the fixed point, increase rounding corners, reduce stress concentration, and improve the bending resistance life.

3.5 After optimizing the EPB wire harness as mentioned above, a bending test was conducted. The bending angle of the wire harness on the bench was reduced, and the stress concentration was significantly reduced. After the entire wire harness bending test reached a life of 1 million times, the appearance of the wire was flawless and no breakage occurred. , the electrical signal transmission is normal.

Figure 6 Optimized cross section and optimized bending test

4 Conclusion

① The potential causes of EPB wire harness breakage are analyzed in depth based on the location where the car EPB wire harness breaks, the broken cross section, the material of the wire, and the installation method.

② The experimental method was used to conduct an in-depth analysis of the stress on EPB wire harness breakage and confirm the cause of EPB wire harness breakage.

③ Formulate a material selection plan for automotive EPB wiring harness multi-core copper wires, define the principles for the outer protective layer of the wire, the length of the wire harness in the movement area, and the material hardness of the installation point. Through comparative analysis before and after the implementation of the improved plan, the accuracy of the optimization plan was verified, which is the first of its kind Provides reference for problem analysis and solution.