The automobile wiring harness connector is an important component used to connect the automobile electrical circuit. Its function is to connect the various circuits in the vehicle electrical circuit to provide a good way for current flow and electrical signal transmission, thereby realizing the normal and stable operation of the circuit. In the assembly of the whole vehicle, the connector plays a vital role in it. Since there are many connection points in the connector, any problem may have very serious consequences, and even cause a traffic accident. Therefore, in the process of designing automotive electrical circuits, the rational selection of connectors plays a vital role. This paper briefly analyzes the selection method of wiring harness connectors from three aspects: electrical performance, mechanical performance, and environmental performance.
Electrical performance The connector is a component used to connect electrical circuits, so its electrical performance should be considered first. Electrical performance mainly considers aspects such as voltage, current, resistance and insulation. The rated voltage is the working voltage, and its value depends on the terminal spacing and insulation material. The connector manufacturer generally provides the highest working voltage, and the low-voltage connector generally has a working voltage of 12V or 24V, while the voltage provided by the manufacturer is generally 50V. The rated voltage of high-voltage connectors suitable for new energy vehicles is as high as 600V. Followed by the rated current, its value is the same as the rated voltage, generally slightly higher than the normal working voltage. Under normal circumstances, the rated current of the connector is to test its heat resistance performance at room temperature. When the temperature exceeds the set value, it will cause electrical circuit failure. Generally, the rated current is provided in the product manual, which is the maximum working current at room temperature. For the high temperature working environment and the multi-hole condition of the connector, the rated current provided by the supplier cannot simply be used for selection. The temperature-current curve of the connector should be used to determine the working current that meets the working environment temperature of the connector and meets the requirements. connector. For multi-hole connectors, especially in the case of high current, the actual selection should be derated according to the number of holes of the connector. In addition, from the perspective of connector contact resistance, the contact resistance measured under the test conditions of low-level contact resistance should be considered for small-signal circuits. For those small-signal circuit connectors that cannot be met by normal tin-plated terminals, consider Use precious metal coatings such as silver or gold to solve. Finally, for the insulation performance of the connector, it mainly refers to the insulation resistance and insulation dielectric strength. The specific value can be obtained by measurement. It is necessary to make a selection based on the insulating material used in the connector and the working environment.
Mechanical properties The mechanical properties of the connector mainly include the insertion force, the mechanical life, the cooperating force and the separation force between the terminal and the sheath, etc., which play an important role in the selection of the connector. As the name suggests, mating force is the force required to separate the plug from the socket. On the premise of ensuring normal power-on, the smaller the plugging force, the better. If the plugging force is too large, the plug cannot be pulled out smoothly, and if the plugging force is too small, it will lead to poor contact. The force is not higher than 75N. Therefore, under the premise of ensuring normal power-on, the smaller the insertion force, the better. Mechanical life refers to the number of times it can be plugged and unplugged. The mechanical life of the general electrical connector is usually 500-1000 times, while the car connector generally meets the requirements of normal conductivity after 10 times of plugging and unplugging, and the conductive performance of silver-plated terminals is normal after 30 times of plugging and unplugging. After the electrical conductivity is normal. The mating force between the terminal and the sheath is affected by the crimping wire diameter of the terminal. When it is less than 1mm2, the mating force is not less than 15N, and when it is larger than 1mm2, the mating force is not less than 30N. The separation force between the terminal and the sheath is related to the size of the connector. For connectors with specifications below 2.8 and above 2.8, the separation force should be greater than 40N and 60N.
Environmental performance Vehicle connectors are widely used, and different parts of the car are often located in different environments. Therefore, in the selection of automotive connectors, environmental factors play a crucial reference role. Environmental factors mainly include temperature, humidity, waterproof and dustproof, etc. The ambient temperature is divided into 5 grades, and the test temperature is generally slightly higher than the ambient temperature. When selecting, first determine the corresponding temperature grade according to the location, and then make the most reasonable choice according to the sheath and terminal material. The humidity of the connector should not be too high, and it is easy to cause a short circuit problem in a humid environment. Therefore, sealed connectors should be used in humid environments. Different positions on the car have different air humidity and water interference levels, and the required waterproof level is also different. The engine compartment, the chassis and the lower part of the engine, the seat and the bottom part of the door near the chassis should generally choose a waterproof sheath. For parts such as the interior of the cab, doors, and the upper part of the seat, non-waterproof connectors can be considered. Generally, with the improvement of waterproof performance, the dustproof performance will also increase accordingly.
Conclusion The selection of the connector is a work that must be paid attention to and done well in the design process of the vehicle wiring harness. It is not only related to the stable operation of the vehicle electrical circuit, but also affects the overall use of the vehicle. In the actual selection process, the electrical performance, mechanical performance, environmental performance and other aspects of the connector should be analyzed to meet the basic requirements of power transmission and electrical signal transmission. According to the characteristics and performance of the vehicle, choose the most suitable type of connector, so as to achieve the ideal line connection effect.
