The matching of the temperature rating of automobile control cables with the operating environment is a key factor in ensuring the safety and reliability of the electrical system.
The relationship between temperature resistance grades and materials
Cables of different temperature resistance grades usually adopt different insulation and sheath materials. For example:
Class A (85℃) : Use Class V or Class E insulating materials;
-H class (250℃) : F-class insulating materials are used.
Irradiation cross-linking technology: It can enhance the temperature resistance grade of cables. For instance, irradiation cross-linked polyethylene or polyolefin insulation materials can reach 150℃ or even higher.
Materials such as PVC, XLPE, and silicone rubber are also frequently used in cables of different temperature resistance grades.
2. Matching of temperature resistance grade with the usage environment
The temperature resistance grade of the cable should match the highest temperature in the actual usage environment. For example:
-40℃ to 125℃ : Suitable for high-temperature areas such as engine compartments and front compartments.
-40℃ to 150℃ : Suitable for high-temperature environments, such as exhaust systems, turbochargers, etc.
-40℃ to 250℃ : Suitable for extreme high-temperature environments, such as braking systems, high-temperature sensors, etc.
3. The relationship between the rated voltage of the cable and its temperature resistance grade
The temperature resistance grade of a cable is closely related to its rated voltage. For example:
Flexible cables for electric vehicles of -1000V and below: The temperature resistance grades increase from 85℃ to 250℃, suitable for cables of different voltage levels.
High-voltage cables for new energy vehicles: Generally, they are required to have a temperature resistance level of 125℃ or 150℃ to meet the operational requirements of high-voltage systems.
4. The relationship between the current-carrying capacity of the cable and its temperature resistance grade
The temperature resistance grade of the cable directly affects its current-carrying capacity. For example:
- Low-voltage automotive wires with a temperature resistance of 100℃ : Recommended current-carrying capacity at a maximum ambient temperature of 70℃.
- Low-voltage automotive wires with a temperature resistance of 150℃ : Also, at the maximum ambient temperature of 70℃, the recommended current-carrying capacity.
-EN 50264 standard: It stipulates the overload temperature range of vehicle-mounted cables at 90 ° C and 150 ° C, which are 160 ° C /50 h and 250 ° C /50 h respectively.
5. Weather resistance and environmental adaptability of cables
Cables not only need to meet the temperature resistance requirements, but also have good weather resistance. For example:
- Temperature cycling test: Perform 100 rapid alternating cycles between -40℃ and +120℃ to check for cracking of the insulation layer.
- Wet heat aging test: Continuously conduct 1000 hours at 85℃ and 85% humidity to evaluate the insulation resistance attenuation rate.
UV exposure test: Simulate sunlight exposure for 2000 hours to detect the embrittlement degree of the sheath material.
6. Flame retardancy and fire resistance of cables
The flame retardancy of the cable is also an important consideration. For example:
Halogen-free flame retardant materials such as magnesium hydroxide (MDH) and aluminum hydroxide (ATH) are often used in cross-linked polyethylene cables.
- Fire resistance performance: The cable must comply with standards such as EN 50306-2, DIN 5510-2, and BS 6853, and is suitable for environments with hazard levels ranging from HL1 to HL4.
7. Mechanical properties of the cable
The mechanical properties of the cable also need to match the usage environment. For example:
- Wear resistance: Suitable for high-wear areas such as braking systems and ABS sensors.
- Flexibility: Suitable for wires in low-temperature environments, such as those on suitcase LIDS.
- Tensile strength: Ensures that the cable is not prone to breakage during long-term use.
8. Cable selection and design
In practical applications, the selection of cables needs to be based on specific requirements. For example:
- Japanese standard cable: Temperature resistance range -40℃ to 120℃.
- German standard cables: Temperature resistance range -40℃ to 150℃, and some special insulating materials can reach -65℃ to 290℃.
National standard cable: Temperature resistance range -40℃ to 105℃.
9. Inspection and verification of cables
To ensure that the performance of the cable meets the requirements, a series of tests and verifications need to be carried out. For example:
- Thermal overload detection: 6H temperature resistance grade +50℃ detection technology, assessing the cable's ability to withstand extreme temperatures.
- Aging test: Conduct long-term aging tests at specified temperatures to assess the service life of cables.
10. Standardization and certification of cables
The selection and use of cables must comply with relevant national and international standards. For example:
GB/T 25085 and GB/T 25087: Stipulate the standards for heat resistance, mechanical strength and color marking of high-voltage cables.
ISO 6722: Specifies the heat resistance grades of cables used in automobiles.
Conclusion
The matching of the temperature rating of automobile control cables with the operating environment is crucial to ensuring the safety and reliability of the electrical system. In practical applications, the appropriate type and material of cable should be selected based on factors such as the usage environment, rated voltage, current-carrying capacity, weather resistance, flame retardancy, and mechanical properties of the cable. At the same time, a series of tests and verifications are also required to ensure that the performance of the cable complies with relevant standards and requirements.
