Automotive Connector Standards and Analysis
Automotive connectors, as key components of the automotive electrical system, are responsible for connecting various electrical components and facilitating the transmission of signals, power and data. With the increasing complexity of vehicle functions, the number and variety of connectors used have significantly increased, from dozens per vehicle in the past to hundreds now, with over a hundred types and specifications ranging from 6.3 to 0.64.
These connectors are distributed in different parts of the vehicle, such as the cockpit, body, doors, engine compartment, and transmission, and due to the diverse usage environments in each part, the performance requirements for connectors also vary. Therefore, a complete and strict set of usage standards is crucial for the selection and application of automotive connectors.
Distribution of automotive connector standards
There are numerous connector standards currently available, ranging from the earlier international standards ISO 8092 and SAE USCAR-2, to the latest revised industry standard QC/T-1067-2017 (replacing QC/T-417) in China. At the same time, many automotive companies have also defined their own connector standards, such as VW 75174 of Volkswagen, GMW-3191 of General Motors, SMTC 3 862 001 of SAIC Group, and Q/JLY J7110195C of Geely Automobile. Due to the abundance of standards, and the fact that there are many similarities as well as certain differences among them.
The definition of the usage environment for connector standards
1. Protection level
The three standards have reached consensus on the definition of the connector’s protection level based on different application positions. It is divided into S1 non-sealed area, usually applicable to the cabin or trunk and other positions; S2 sealed area, such as the engine hood or exposed area (including the doors); S3 high-pressure water spray area, for specific exposed areas. This classification ensures that the connector can effectively resist external factors in different environments and guarantee the stability of the electrical connection.
2. Temperature Grades
Depending on the different application positions of the connectors, the three standards all divide the operating temperature into 5 grades. However, there are slight differences in the specific application of these grades. QC/T-1067 and USCAR- 2 explicitly do not recommend using products with a temperature range of -40 to 85℃, while GMW – 3191 recommends this temperature range for the experimental environment of connectors installed in the cab.
For example, connectors in the engine compartment need to withstand higher temperatures, and generally, connectors with high-temperature tolerance grades are selected; while the temperature in the cabin is relatively stable, the requirements for temperature grades are relatively lower. A reasonable division of temperature grades helps ensure that the connectors can work normally in different temperature environments, avoiding performance degradation or failures due to temperature issues.
3. Vibration Levels
By comparing the detailed vibration frequencies and power spectral density (PSD) in the standards, it can be seen that the vibration levels V3, V4, and V5 defined in QC/T – 1067 and USCAR-2 correspond respectively to the levels 2/4/3 in GMW-3191. At the same time, GMW-3191 defines the vibration levels and applicable parameters for transmission connectors, while USCAR-2 and QC/T – 1067 define the vibration levels and applicable parameters for connectors installed on components connected to the engine but not to the components subject to severe vibrations.
When selecting connectors for a certain function, it is necessary to first determine the location of the function, and based on the location, determine the temperature level, vibration level, and protection level of the required compatible connectors, thereby achieving the best selection. For example, connectors installed on the wheel area need to have a high vibration level and good protection level to adapt to harsh working conditions.
The definition of mechanical properties in connector standards
In terms of the performance related to terminals, the terminals themselves must have a certain bending resistance to prevent bending or cracking during pressing, assembly and usage; the insertion force between terminals should be moderate, as too small an insertion force may lead to unreliable contact, while too large an extraction force is not conducive to maintenance; there are also strict requirements for the insertion force, holding force, and thrust force between terminals and connectors to ensure a secure and stable connection. For example, in scenarios with frequent insertion and extraction, the insertion force and durability of the terminals need to be given particular consideration.
The insertion force, separation force, unlocking force and polarization test between connectors are crucial for the ease and accuracy of assembly between connectors; the secondary locking (TPA) assembly force and retention force of connector terminals, as well as the secondary locking structure (CPA) assembly force and retention force of connectors, can effectively prevent terminal loosening or detachment; the mechanical strength of the connector assist structure, the mechanical strength of the connector fixation structure and the retention force of the sealing ring, etc., ensure the overall stability of the connector in complex environments.
Conclusion
The standards for automotive connectors have been strictly and meticulously defined across various aspects, including usage environment, mechanical and electrical performance, etc. These standards are crucial for ensuring the quality and reliability of automotive connectors. They provide significant guidance for automotive manufacturers and connector manufacturers in product selection, design, manufacturing, and quality inspection. As automotive technology continues to evolve, the standards for connector usage will also be continuously improved and updated to meet the new demands and challenges of the industry.
