Analysis Of Mounted Resonant Frequency Of Piezo-electricAcceleration Sensor And Its Application

Piezoelectric acceleration sensor is based on piezoelectricity of piezoelectric material, which can transform information of vibration acceleration into electric charge or voltage. Because of its excellent performances in usage such as its simple structure, high reliability, piezoelectric acceleration sensor has been used widely in measurement of vibration and impact.In this paper, the resonant frequency of vibration measurement system with a piezoelectric acceleration sensor mounted on a magnet base is researched. A mechanics model of measurement system, which is composed of magnet base, Piezoelectric acceleration sensor and measured bearing, is set up on the basic of mechanics theory. The mounting resonant frequency of the system is deduced from the mechanics model. By analysis of the mounting resonant frequency, it can be seen that the radius of bottom surface, height and magnetization intensity of the magnet base are the key factors influencing on the mounting resonant frequency. Four emulators based on Matlab are designed to show the relations of mounted resonant frequency to the key factors.The simulation results have shown that a smaller radius and a larger height are useful to promote the mounting resonant frequency when height is less than five Millimeter and a smaller radius and height are beneficial to promote the mounting resonant frequency when height is over five Millimeter.For verifying the theoretical analysis mentioned above, a virtual instrument is constr- ucted to measure and analyze acceleration signals of bearing vibration. The results of autoregression analysis on the measured signals have shown the validity of the theoretical analysis. Comparing with the probe type of piezoelectric acceleration sensor, the magnet based acceleration sensor could acquire the signals with wider frequency band.The difference between the theoretical analysis and experimental results is discussed and reasonable suggestions to improve the measurement of bearing vibration are presented.A general method as reference selected the magnet base of acceleration sensor is also given in this paper for measurement of bearing vibration.