Research On The Steam Pressure Sensor Of General Automobile Oil Tank

As one of the pollutants emitted by vehicles,hydrocarbons cause serious damage to the environment and human health.By installing fuel evaporation management system,the hydrocarbon emission of vehicles can be reduced by 20%.The fuel evaporation management system has gradually attracted people’s attention.As an important part of the fuel evaporation management system,the tank pressure sensor constantly monitors the pressure in the tank and prevents the leakage of fuel vapor.Hence,it plays an important role in protecting the environment.In order to improve the output accuracy and service life of the sensor,the structure,packaging technology and temperature compensation method of the sensor are explored in this work.The structure and size of the sensor chip are designed with the small deflection deformation theory to calculate the thickness of the chip.According to the maximum power consumption of silicon material,the size of Wheatstone bridge resistance is calculated.The finite element software is employed to analyze the change of the sensor diaphragm under force and the voltage output of Wheatstone bridge on the diaphragm.The packaging structure and technology of the oil tank pressure sensor are demonstrated.In the aspect of packaging technology,the influence of different Young’s modulus of adhesive and different thickness of adhesive on chip stress are analyzed by COMSOL software.Two different sealing methods of the sensor are compared,and the optimal sealing form of sealing ring are illiustrated.By analyzing the causes of chip failure and package failure of pressure sensor,the solution of multi lead bonding is performed.By using the voltage output values measured at different temperatures after the sensor is encapsulated,the static parameters of the sensor are described.The causes of temperature drift of piezoresistive pressure sensor are studied in this work,and the compensation schemes of zero temperature drift and sensitivity temperature drift of pressure sensor are provided.The MLX90328 signal conditioning chip is employed to compensate the temperature of the oil tank pressure sensor.The parameters of the oil tank pressure sensor are calibrated at-40℃,25℃ and 90℃,respectively.The sensor test platform is built.The sensor durability test,continuous high temperature experiment as well as medium compatibility test between sensor and fuel,and low temperature wake-up experiment are carried out.