Study On The Technology And Application Of Piezoelectric Electro-Pneumatic Invertor And Membrane Electro-Pneumatic Invertor

The electron-pneumatic inverter is the main accessory of the pneumatic actuator and is the indispensable key equipment in the automatic industrial production. It's used to achieve the information conversion and the energy conversion in the automatic control instruments and systems. With the development of the micro-electronic technology, the control theory and the computer technology, the electron-pneumatic invertor is tending to the electronic or intelligent production and taking place of the traditional mechanical structure. At the same time, the higher requirement is advanced to electron-pneumatic invertor device. Base on the successful researching of the EPI device and analyzing the theory of piezoelectric actuator, the paper design a new electron-pneumatic invertor with piezoelectric actuator. Furthermore, study on the static character theory and experiment and establish a high efficient control system which kernel is microprocessor. It provides the basis of theory to prepare the new and intelligent electron-pneumatic invertor or electron-pneumatic positionor in the future.EPI device is I/P convetrtor unit which is the kernel of electric-pneumatic invertor.The paper has researched thoroughly the problem of mechanism of the I/P convetrtor unit losing efficiency and being trouble to debug, which is based on the design of EPI structure and control circuit. A lot of experiments on the temperature and the fatigue are done to make the stability and the reliability better. The relation between up and down flat diaphragms is achieved through the theoretical research of bending displacement of thin diaphragms, which raise efficiency to succeed in debugging and provides foundation of computer virtual debugging.The piezoelectricity mechanism is explicated in the paper. Also the relationship between the physical effects of the piezoelectric crystals is analyzed, and the thermo-dynamics equation, which is related to the piezoelectric crystal performances of the electric, thermal and elastic performance is given according to the thermodynamics theory. In the meantime, the characteristics is analyzed and discussed systematically about the polarization mechanism, the displacement, the electro-mechanical coupling, the dielectric consumption, the temperature and so on of the piezoelectric ceramic. These are the basic of the analysis about the flexure displacement of the piezoelectric bimorph crystal.The mathematical model of piezobimorph driving displacement is studied and analyzed. The piezoelectric bimorph crystal usually has two structures: cantilever beam structure and compound disc. Considering piezo-bimorph actuators of double-sided and single-sided, the formular on displacement model is derived by forcing analysis. Influnce of elastic beams thickness and material characters are discussed by numerical simulation on computer. According to the energy methord in the approximate analysis method about the little flexibility bending of the thin shell and drawing on the vibration methord to the piezoelectric vibrator, a driving displacement model of the compound disc is deduced and the main influence to the compound disc static bending displacement is given. The results of experiments proved exactitudes of the formulas. The model enriches the theoretical system of the piezoelectric micro-actuator.Basing on the developing of membrane EPI, the author designes two new structures,which are the piezobimorph cantilever beam and the compound disc. Both of them directly use the piezoelectric actuator as the nozzle/flapper. As to the piezoelectric cantilever beam inverting equipment, by the analysis of theoretical equation about the bimorph crystal bending displacement, the airflow's effect to the board and the characteristic of the airflow route in the inverting instrument, a theoretical equation is obtained about the atmospheric pressure in the back pressure room going along with the external voltage. The fitting curve of the compound disc driving displacement is obtained by the linear regression of the experimental data. A...