3. Principles and Design of Safe Layout for High Voltage Wiring Harness
In addition to the aforementioned two methods of high voltage wiring harness layout, we should also consider principles such as safety and ease of maintenance.
(1) Avoidance of Vibrational Areas Design
When arranging and securing high voltage wiring harnesses, they should be kept away from areas with intense vibrations (e.g., air compressors, water pumps, and other vibration sources). The high voltage wiring harness should be connected to high voltage devices without relative vibrations. If it is not possible to avoid these areas due to structural layout or other factors, sufficient extra length of the high voltage conductor should be provided based on the vibration amplitude and maximum envelope of moving parts in the area where the harness is installed. This is to prevent the harness from being subjected to tension or pulling forces.
When vehicles travel on rough roads for extended periods, it is prone to cause displacement or detachment of high voltage wiring harness fixing points. Consequently, the distance between two fixing points instantly increases, exerting tension on the harness and leading to the detachment or virtual connection of internal nodes, resulting in an open circuit. Therefore, the length of high voltage conductors should be controlled reasonably. It should provide enough surplus length to counteract the stress caused by movement and dragging, while avoiding excessive length that may cause twisting of the harness.
(2) Avoidance of High Temperature Areas Design
When arranging the wiring harness, high-temperature components in the vehicle should be avoided to prevent the wires from melting or accelerating aging due to high temperatures. Common high-temperature components in new energy vehicles include air compressors, brake air pipes, power steering pumps, and oil pipes.
(3) Design of High Voltage Conductor Bend Radius
Whether it is to avoid compression or excessive vibration, attention should be paid to the bend radius of the high voltage wiring harness during layout. This is because the bend radius of the high voltage wiring harness has a significant impact on its resistance. If the harness is excessively bent, the resistance of the bent section increases, leading to increased voltage drop in the circuit. Prolonged excessive bending can also cause aging and cracking of the insulating rubber of the harness. The following diagram illustrates an example of incorrect design (Note: The minimum inner bend radius of high voltage conductors should not be less than four times the outer diameter of the conductor):
Correct arrangement example at junction (left) Incorrect arrangement example at junction (right)
Therefore, both in the initial design phase and during the assembly process, we need to avoid excessive bending of the wires at the junctions. Otherwise, there may be a risk of electrical leakage in the sealing components behind the junction. The high voltage wiring harness exiting from the rear of the connector should have a straight orientation, and the high voltage conductors near the rear of the connector should not be subjected to bending forces or rotation.
4. Design for Sealing and Waterproofing of High Voltage Wiring
In order to enhance the mechanical protection and waterproofing capabilities of the high voltage wiring harness, sealing measures such as sealing rings are employed between connectors and at the locations where the connectors connect to the cables. These measures prevent the entry of moisture and dust, ensuring a sealed environment for the connectors and avoiding safety issues such as short circuits, sparks, and leakage between contact parts.
Currently, most high voltage wiring harnesses are protected by wrapping materials. The wrapping materials serve multiple purposes such as abrasion resistance, noise reduction, heat radiation isolation, and aesthetics. Typically, orange high-temperature-resistant flame-retardant corrugated pipes or orange high-temperature-resistant flame-retardant fabric-based sleeves are used to provide complete coverage. The following diagram shows an example:
Sealing measures examples:
Sealing with adhesive heat shrink tubing (left) Sealing with blind plug in the connector (right)
Sealing with adhesive sleeve at the connector end (left) Prevention of U-shaped layout for harness (right)
Chengdu Yiwei New Energy Automobile Co., Ltd is a high-tech enterprise focusing on electric chassis development, vehicle control unit, electric motor, motor controller, battery pack, and intelligent network information technology of EV.
Contact us:
yanjing@1vtruck.com +(86)13921093681
duanqianyun@1vtruck.com +(86)13060058315
liyan@1vtruck.com +(86)18200390258
Post time: Dec-28-2023
