With the rapid development of the automobile industry, numerous accidents caused by vehicle spontaneous combustion due to excessive engine temperatures have raised widespread concerns in society. Therefore, this paper proposes a high-precision temperature measurement method based on various thermocouples. Firstly, one end of K/T/E-type thermocouples is attached to the outer surface of a constant temperature oil tank. The corresponding voltage and temperature values are recorded every 30 minutes as the temperature of the oil tank increases, and a voltage-temperature curve is plotted. The Seebeck coefficient of the K-type thermocouple is 41.55 μV/°C, the Seebeck coefficient of the T-type thermocouple is 38.84 μV/°C, and the Seebeck coefficient of the E-type thermocouple is 57 μV/°C. Subsequently, the thermocouples are applied to the surface of the automobile engine, and the multimeter readings are continuously recorded after the engine is started. Based on the Seebeck coefficients of the thermocouples, the temperature of the GG-K-30 K-type thermocouple rises rapidly from approximately 12°C to 80°C within 0.5-4.5 minutes, further increasing to around 120°C within 4.5-9.5 minutes, and then stabilizing at approximately 122°C. The temperature of the TT-K-30 K-type thermocouple rises from about 7°C to 75°C within 0.5-4.5 minutes, reaching approximately 120°C within 4.5-10 minutes, and then stabilizes at about 124°C. The temperature of the T-type thermocouple increases from around 12°C to 80°C within 0.5-5 minutes, rises to about 120°C within 4.5-9.5 minutes, and then stabilizes at around 123°C. The temperature of the E-type thermocouple with a length of 2000 mm rises from around 8°C to 86°C within 0.5-6.5 minutes, further increasing to 120°C within 6.5-10.5 minutes, and then stabilizing at about 122°C. The temperature of the E-type thermocouple with a length of 1000 mm rises from approximately 5°C to 75°C in 0.5-5.5 minutes, reaching 120°C in 5.5-10 minutes, and then stabilizing at about 121°C. Experiments show that the thermocouple temperature measurement method has good accuracy and stability, allowing for real-time continuous measurement of engine temperature and providing danger warnings. This method offers an effective and reliable solution to the temperature- related issues of automobile engines.
