Development Of Self-Renewing Thin Film Temperature Sensor For Axle Temperature Measurement Of High-Speed EMU

With the continuous speed improvement of high-speed Electric Multiple Unit(EMU),a higher requirement for train safety technology is put forward,among them,train axle temperature monitoring is one of the key factors to ensure the safety of train operation.If the abnormal change of axle temperature can not be monitored in time,it will affect the train normal operation and even endanger life and property security.Due to the limitation of response speed,temperature measurement range,working conditions and so on,the existing axle temperature sensor is difficult to realize the transient temperature measurement of high-speed EMU axle box bearing accurately and in real-time.In view of the technical problem of transient axle temperature measurement for high-speed EMU,a self-renewing thin film temperature sensor for transient axle temperature measurement of high-speed EMU is developed.The static and dynamic characteristics of the self-renewing thin film temperature sensor are investigated based on the working principle of thermocouple.The static characteristic mechanism of the sensor is studied through the Seebeck effect and the absolute thermoelectric potential.The dynamic characteristic of the sensor under the radiant heat transfer boundary condition is studied by the lumped heat capacity method.The matrix structure,NiCr/NiSi mask,special fixture and armour sleeve of the self-renewing thin film temperature sensor with thermoelectrode overlap area lengths of 4mm,6mm and 8mm are designed.The preparation of Al2O3 insulating thin film,NiCr/NiSi thermoelectrode thin film and SiOxNy protection thin film are prepared by magnetron sputtering,and the properties of Al2O3 insulating thin film and NiCr/NiSi thermoelectrode thin film are characterized.A set of static and dynamic calibration system is developed based on Lab VIEW,and the static and dynamic calibration of the self-renewing thin film temperature sensor are completed by using this system.The results show that the Seebeck coefficients are 37.81?V/K,37.78?V/K and 37.83?V/K respectively,the change rate of Seebeck coefficient is less than 0.2%,the nonlinear fitting error is less than 0.4%,and the dynamic response time is 53.2ms,57.8ms and 51.4ms respectively.The results show that the static and dynamic characteristics of the self-renewing thin film temperature sensor have no relevance to the length of thermoelectrode overlap area.The common problems and solutions in axle temperature monitoring system are studied.A set of axle temperature monitoring system is developed based on Lab VIEW,which integrates temperature measurement,data acquisition,data processing,data storage and axle temperature alarm.After testing,the system realizes real-time monitor and respond accurately to the state of axle temperature rise,warm axle and hot box.The self-renewing thin film temperature sensor abrasion test is carried on by using this system,and the results show that the static and dynamic characteristics of the self-renewing thin film temperature sensor are not affected as the temperature measuring end are worn for a certain length,and the prepared self-renewing thin film temperature sensor still can measure temperature continuously and accurately.