The Application of Rubber Seal on Automobile Wiring Harness

Harness seal

More and more attention is paid to the durability and reliability of auto parts. As a protective material, rubber parts are widely used in automobiles. The importance of sealing rings is self-evident, especially for the wiring harness protection of the engine compartment and the lower chassis of the car. , Because usually, these two places are more likely to be in a harsh environment. There is a "wet zone" concept. Generally speaking, we call the "wet zone" the area where the engine compartment and the lower body of the car are exposed to the air and often affected by rain and water. Correspondingly, the cockpit and luggage Boxes and other parts are basically not affected by rain, this part is called "dry zone".

One of the biggest functions of the Wire Harness Seal is to isolate the wet zone and the dry zone. This is an application. A common part is to install one between the engine compartment and the cockpit to separate the dry zone from the wet zone; There is a sealing ring that needs to be assembled on the left and right rear ABS wiring harnesses, specifically under the rear seats (such as golf), there is a sealing ring that separates the inner and outer parts to ensure that the water at the bottom will not leak into the driver during the driving room.

Each qualified wire harness will go through a hermetic sealing test to ensure that the sealing ring on the wire harness can function. Generally, in the wire harness factory, we use vacuum testing and testing equipment to work.

The working principle of the equipment is very simple. Place the sealing ring on the mold, and the equipment provides a continuously increasing pressure value to extract the air inside. Within a certain time and pressure value, if the sealing ring can withstand it, it is a good product. On the contrary, there are quality problems.

Wire Harness Seal

Connector sealing

The electronic appliances and wiring harness in the dry zone are less affected by high temperature/high humidity and chemicals/dust. The wet zone is just the opposite. If the sealing is not good, it may cause water in the appliances and the wiring harness, causing internal circuit short circuit/corrosion, etc., which will directly lead to functions Failure, this requires automotive wire harness seals to be sealed and protected. For example, the ESP-SG plug of the engine compartment in the Audi A3 project has an air-tight design. Open the connector and you can see it. A layer of the sealing ring (with oil), its sealing performance is directly related to whether the function is normal.

There are two main ways for electronic components such as connectors to enter the water. The first is that external liquid penetrates into its interior by gravity, such as connectors without sealing rings, or moisture from the internal connection points of the wiring harness (such as unprotected solder joints). /Crimping point/grounding point) enter; here we emphasize the word "siphon", because general electrical appliances have a certain temperature when working, and the internal air forms a certain pressure. When the work stops, the temperature drops and the internal pressure is also small. If the connector is not properly sealed, water vapor will enter the interior along the gap between the multiple strands of copper wires, resulting in functional failure; therefore, the connector in the wet area generally requires a sealing ring (pad).

For the sealing test of the connector, the general wiring harness manufacturer is integrated in the electronic test bench, and the test module corresponding to the connector will have its own sealing test, and also give it a rated pressure value while testing its continuity Test the sealing performance.

Sum up

The sealing ring is a very important part of the wire harness. Its quality is directly related to the function of the wire harness. Whether it is used directly on the wire harness or in the connector, some problems will occur. The common problem of the former is that the use of materials or rubber is Improper handling in the vulcanization process, leaks or spots on the surface; the common problem of the latter is that the internal sealing ring is not assembled in place and the whole is not on the same plane, causing air leakage. Finding the root cause of the problem and solving it as soon as possible, and taking preventive measures are skills that all wire harness practitioners should master.