Development Of Acicular Thin Film Sensor For Temperature Measurement Of High Speed Train Brake Disc

With the development of science,technology and the continuous exploration of people’s outer space,China’s rail transportation business has achieved leaping development.The increasing speed of high-speed train and railway station make the reliability of the brake system in the high speed train gradually become the hot spot that the enterprises and experts pay attention to.Under the condition of emergency braking,the main way of braking is to generate braking power by friction between brake disc and brake pad.In the case of high speed braking,the thermal load of the brake disc is huge,and when the load limit of the brake disc is exceeded,it will be damaged in varying degrees.Therefore,the determination of brake disc temperature is one of the important references for understanding the performance and life of the brake disc.Reliable brake disc thermal protection system and real-time temperature detection system are guarantee for high speed braking safety.At present,there are still many problems in the temperature measurement technology of high-speed train brake disc,and the conventional temperature sensor cannot meet the detection demand of the high speed train brake disc transient temperature.In view of the above problems,a needle thin film thennal sensor is developed,which realizes the transient temperature measurement requirements of the brake disc,and provides reference data for the study of the high speed train brake disc transient temperature study.In this paper,according to the working principle of high speed train brake disc transient temperature measurement,the static thermal simulation of temperature measurement experiment is carried out,and the design of a needle like thin film sensor suitable for high speed train brake disc transient temperature measurement is proposed.According to the requirements and previous research results,the structure and preparation process of the sensor are studied.The sensor size is smaller,the connection of compensation wire is more reliable,and the sensor installation size can be customized.The experiment of sensor preparation and dynamic and static calibration is completed.The theoretical analysis of the heat transfer process of the dynamic calibration experiment is completed,and the heat transfer model and finite element simulation analysis are carried out by using Creo and Ansys-Workbench software.The diameter of the sensor is 1.5 mm and the diameter of the hot junction is 0.3 mm.The thickness of the film is 788 nm and the thickness of the insulation protection film is 1053 nm.In the calibration experiment,the stability of the sensor is good and the consistency is strong.The Seebeck coefficient is about 41.99 μV/℃ in the range of 50～650 ℃,the nonlinear fitting error is less than 0.36%and the time constant is 0.048 ms,which can meet the requirement of the transient temperature detection of high speed train brake disc.The calibration results of multi-sensor showed that the needle shaped thin film sensor prepared by this process had good consistency.Through the combination of theoretical simulation and experimental results,it is found that the larger the thickness of the film is,the slower the dynamic response speed of the film sensor is,and the increase of the thickness of the insulation film will slow the dynamic response of the film sensor.