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The wiring harness is the nervous system of the vehicle's electrical appliances, and it plays a vital role in the realization of the vehicle's electrical functions. The electrical safety of the entire vehicle has always been the most concerning issue for all automobile manufacturers. The working environment in each area may have an impact on the wiring harness. Water-resistance is content that cannot be ignored in the wiring harness design. Therefore, this article will discuss the waterproofing of the wiring harness. Make a brief analysis of the design.
According to the distribution of the dry and wet areas of the whole vehicle, we divide the whole vehicle wiring harness into the following parts: front cabin wiring harness, powertrain wiring harness, instrument wiring harness, indoor wiring harness, ceiling wiring harness, four-door wiring harness, and back door wiring harness. According to the distribution of the dry and wet areas of the vehicle, the front cabin wiring harness, powertrain wiring harness, and four-door wiring harness are located in the wet area. This part of the money harness needs to be waterproofed and the parts connected to the room should be sealed with rubber. The rest of the wiring harness is located in the dry area, and the connector does not need to be waterproof, but in order to prevent water from entering the room when connecting to the outside world, corresponding waterproof treatment should be done.
There are four winding methods for the wiring harness of the whole vehicle, semi-encapsulation winding method, thick winding method, double winding method, and 2/3 packaging winding method. Among them, the whole vehicle wiring harness mostly adopts the semi-encapsulated winding method or the rough winding method. The so-called semi-encapsulated winding method is to bundle the wires into a bundle. The width of the insulating tape is about 1/2 times. The rough winding rule is to bundle the wires into a bundle, and the spacing width of the insulating tape is 1.5 times the width of the tape. It is required that the adhesive surface of the insulating tape is not exposed.
The front cabin wiring harness and powertrain wiring harness are in direct contact with the outside world and need to be treated with special waterproofing. The wiring harness requires semi-encapsulated winding; there is a high probability that the door wiring harness will come into contact with water in the event of rain or car washing, so the door wiring harness also needs to be made Special waterproof treatment requires the use of a semi-encapsulated winding method to prevent water from entering the wiring harness and causing a short circuit to affect the safety of the entire vehicle. For the wiring harness that needs special waterproof treatment, the branch needs to be cross-wound, and the wiring harness must not be exposed; the area where the waterproof rubber ring and through-hole rubber sleeve are added, the wiring harness is required to be semi-encapsulated first, and then the rubber ring or rubber sleeve Double winding method with wiring harness.
Since the winding of the wire harness is essential to waterproofing, it must be wound as required to ensure the safety of the entire vehicle.
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There are two main functions of the whole vehicle connector. One is to realize the docking with electrical components, to ensure the reliability of signal transmission, and to ensure insulation and prevent short circuits; the other is to use the connector itself with a positioning clip to prevent the generation of the connector move.
In principle, the connectors outside the cab should be of waterproof type. For example, the connectors in the engine compartment should be equipped with waterproof rubber sealing plugs. Due to the influence of sealing, when the waterproof connector works, heat will be generated at the contact point, resulting in a temperature rise. It is generally believed that the working temperature of the waterproof connector is equal to the sum of the ambient temperature and the temperature rise of the contact. Therefore, the temperature resistance characteristics of the waterproof connector should be taken into consideration when selecting the waterproof connector.
Sealing includes wiring harness inline points, grounding points, and via protection. Due to the siphon phenomenon, the internal temperature of the electrical module will rise when it works, and when it stops working, the temperature will gradually decrease, resulting in a decrease in internal pressure, and the water in the wiring harness can penetrate from the loosely sealed place and follow the pressure difference. The gaps between the strands of copper wires infiltrate the electrical module, causing the electrical module to malfunction. To deal with this phenomenon, in addition to the use of waterproof connectors, it is also necessary to seal the wiring harness inline points and ground points. The most common way is to use a glued heat shrinkable tube for sealing.
When the wiring harness needs to pass through the body sheet metal hole, a rubber protective cover must be added for protection. It is recommended that the interference is greater than 40mm, and the flanging design is required to protect the wiring harness, waterproof, and seal.
Generally, there are two types of vias. One is a simple sheet metal hole, which does not involve moving parts. At this time, pay attention to the relative position of the wire harness before and after the via. The outdoor part of the wire harness is required to be lower than the indoor wire harness; for moving parts It is necessary to fully consider the design of rubber parts and interfaces to ensure that there is no interference and friction during the movement. Consider the relative positions of the sealing and holes of the rubber parts, and try to make the outdoor hole lower than the sheet metal hole in the connection room.
The main point of the electrical system's water intake is that the water relies on its own gravity to penetrate into the electrical system. In addition to the use of conventional waterproof materials for protection, the waterproof function can also be achieved through a reasonable three-dimensional layout. First of all, the whole vehicle grounding is a weaker waterproof link, which is likely to cause water to penetrate the electrical system. Therefore, the layout of the vehicle’s electrical appliances must be fully considered from the early design stage. The electrical installation point must be higher than the grounding point, and the wiring harness must be used. The installation direction is downward so that the optimization of the installation position can effectively solve the water seepage problem caused by the water's own gravity; secondly, the wiring harness arrangement closer to the drainage point of the whole vehicle, such as the door wiring harness and the rear protection wiring harness, because there will be raindrops. It falls on the wire harness, so this part of the wire harness needs to be fixed to its lowest point, so that the water dripping on the wire harness flows to the outside of the car by the wire harness, so as to achieve the purpose of protecting the electrical system.
We are a manufacturer of automotive wire harness seals, please feel free to contact us if you need them.
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