With high temperatures caused by global climate change becoming the norm, the aging resistance of cars under high temperature conditions, the stability of electronic appliances, and the volatility of VOC gases inside the car pose new challenges to vehicle safety. The temperature in summer is getting higher and higher, and the accompanying heat stroke has a serious impact on people’s daily travel. Under this climate background, the durability of the car’s paint, the anti-aging performance of interior materials, the stability of electronic equipment and the release of VOC gas will all directly affect the driving safety.
To address this challenge, relevant industries have started conducting “high-temperature and high humidity solar simulation” test, and a certain car has undergone over 300 hours of high-temperature light exposure testing. The test results show that the car model has no discoloration on the paint surface under extreme high temperatures, and the gap between the interior and exterior parts is much lower than the industry standard. The VOC volatilization is much lower than the national standard, and the vehicle grade electronic and electrical equipment has also passed the test smoothly, demonstrating its new reliability standard in compact joint venture SUVs.
In this test, the reliability of the vehicle was rigorously tested under high temperature and lighting conditions. The test is conducted in a professional environment, with a constant air temperature of 45 degrees Celsius in the laboratory. In addition, the test chamber is equipped with a full spectrum illumination of 1000 ± 100 W/m ², which is very rare in natural environments.
Under the combined effects of extreme temperature and lighting, the aging resistance of materials in new passenger cars has been greatly challenged. The test results showed that the highest temperature of the vehicle’s dashboard reached 106.2 degrees Celsius, the rear door trim panel was 91.6 degrees Celsius, the coat rack was 90.7 degrees Celsius, the front bumper was 82.2 degrees Celsius, and the cabin air temperature was also 81.8 degrees Celsius. These data reveal the vehicle’s ability to withstand high temperatures under extreme conditions.
1 Paint color deviation test
According to the standards of the film and television industry, the average Delta E value of color change is maintained at 0.2
Under prolonged exposure to hot weather and intense sunlight, the temperature of surface metal and decorative components of vehicles may rise to 60 to 80 degrees Celsius. In this case, the vehicle paint surface not only has to withstand high-intensity UV radiation, but also accelerates its aging process, resulting in color loss and cracking. The purpose of this experiment is to accurately evaluate the degree of color change in the paint surface, using Delta E as a color perception difference indicator. The higher the value of Delta E, the more significant the color deviation. Normally, the Delta E threshold adopted by the industry is 1.5, which is the upper limit of color differences that can be recognized by the human eye. In ordinary smartphones, this indicator is usually controlled below 1.
According to relevant testing standards, the color difference rating standard in the automotive industry is Delta E less than 1.5, which means there is no color difference. Color difference tests were conducted on key vulnerable parts of passenger cars, such as exterior paint, interior dashboard, door interior, center console armrest, and seat headrests. After 300 hours of high-temperature exposure, the maximum color difference Delta E of these parts does not exceed 0.46, the minimum value reaches 0.04, and the average value is 0.20. All new passenger car body paints use products from internationally renowned chemical companies, which are two-component water-based high-temperature paints and comply with STLA global technical standards. They have completed over 20 rigorous tests, including more than 1500 hours of UV and thermal cycling tests, to ensure that the vehicle’s paint surface can last as long as it is used in any corner of the world.
2 High temperature whole vehicle gap test
After being exposed to ultra-high temperature, the maximum gap between the interior and exterior decorative parts of the car changes by less than the diameter of a silk thread.
The various noises and vibrations caused by high temperatures often trouble car owners. At extreme temperatures, materials such as steel, aluminum, and plastic inside vehicles can expand and contract, leading to increased gaps and, in severe cases, even causing vehicle shaking or functional failures. The DTS standard for complete vehicles specifies the clearances and tolerances during the vehicle design and manufacturing process. At present, the automotive industry generally controls the clearance between vehicles to no more than 0.2mm.
After 300 hours of ultra-high temperature exposure, the gap between the interior and exterior decorative parts of the new passenger car changed from a minimum of 0.0mm to a maximum of 0.1mm. This difference is even less than the diameter of a silk thread, almost reaching the limit that mechanical workers can distinguish. In contrast, most car brands have a standard of 0.2mm for gap variation at high temperatures, and the gap difference of new passenger cars at high temperatures is significantly better than twice the industry average, making them industry-leading.
3 High temperature testing of electronic appliances
The hot summer often causes the air conditioning of vehicles to fail and the temperature inside the car to rise sharply after being exposed to direct sunlight. With the advent of the intelligent era, the auxiliary driving system of vehicles has put forward higher requirements for the stability of electronic and electrical equipment. High temperatures may pose a threat to the active safety systems of vehicles and increase the risk of traffic accidents.
In the testing, the air temperature inside the new passenger car reached 81.8 ℃ and the dashboard temperature even reached 106.2 ℃ under continuous high-intensity irradiation for more than 300 hours. Even in such extreme high temperature environments, air conditioning systems, multimedia systems, and intelligent networking systems can all work normally.
To meet the reliability requirements of electronic and electrical equipment under extreme temperature differences, the new passenger car is equipped with vehicle grade chips and electrical equipment, which can work stably at temperatures ranging from minus 45 ℃ to 120 ℃. In addition, automobiles contain tens of thousands of control chips and mechanical components, which need to be integrated together to ensure system level safety and reliability, reflecting the company’s manufacturing strength and verification standards. For example, the all-new passenger car has undergone two more rounds of validation than conventional vehicles, which means an additional 300 rigorous inspections. The vehicle has also passed tests on 12 extreme road surfaces, over 1100 vehicle tests, and over 2 million kilometers of durability verification, ensuring sufficient quality assurance.
High temperature and odor test inside the car: using highly environmentally friendly materials, VOC emissions meet the standards for children’s green cabins
The odor produced by vehicles exposed to sunlight in summer is not only uncomfortable, but may also cause damage to human skin and respiratory system, and even lead to cancer. TVOC gas emissions are an important indicator for measuring the type and degree of odors inside a car. Under standard testing conditions, the peak volatilization of VOC gases in vehicles can last for 3-15 years, covering the entire vehicle lifecycle. As the temperature increases, the volatilization rate of VOC gases will further accelerate, posing a threat to human health.
According to the standard, the testing of VOC gas emissions from vehicles is usually conducted at room temperature of 25 ℃, and once it meets the standard, it can be put on the market for sale. On this basis, the new passenger car not only raises the temperature inside the car to about 60 ℃, but also extends the high temperature exposure time to 8 hours (the national standard is 3.5 hours) to ensure the safety of the air quality inside the car.
Under strict conditions, the TVOC (Total Volatile Organic Compounds) content of new passenger cars is only 1.125mg/m ³, far lower than most vehicles on the market. According to a survey conducted by the Beijing and Tianjin Consumer Associations on 36 passenger cars, only 3 vehicles had a TVOC content below 2mg/m ³ at high temperatures. The formaldehyde content of the new passenger car in the high-temperature VOC test is 0.072mg/m ³, which is better than the national standard of 0.10mg/m ³ and even meets the indoor formaldehyde standard (0.08mg/m ³). Its toluene content is 0.087mg/m ³ and ethylbenzene content is 0.024mg/m ³, which are far lower than the national standards and only 1/5 of the national requirements.
4 Conclusion
The sunshine simulation testing equipment provides a high standard solution for vehicle testing in the era of high temperature normalization. It not only verifies the performance limits of vehicles in extreme environments, but also drives collaborative innovation in fields such as materials science, electronic packaging, and environmental protection processes, providing the industry with a high-temperature reliability research and development direction from “passive detection” to “active design”.