Theoretical And Experimental Research On Piezoelectric Pumps Driven By Large Actuators

Traditional pumps, which are perfect theoretically, methodically, and technically, are generally driven by electric-magnetic machines or motors. With the development of science and technology, new kinds of actuators come into being one after one. The old pumps are changing. Piezoelectric pumps are based on the reverse piezoelectric effect which can be stated as follows: a displacement is produced when a piezoelectric material is put in an electric field, to drive the liquids. Since the first piezoelectric model is put forward, piezoelectric pumps have drawn more and more attention of the world with its unique working ways and performance.Most of the research on piezoelectric pumps now is focused on micro-pumps characterized by its micro structure. However, there are a lot of limitations. In some case where heavy quantity and high pressure are required, the existing micro-pumps are apparently unsuitable. So research on large piezoelectric pumps is needed. This paper mainly studies large piezoelectric pumps including the theory and working performance, and acquires the optimum value of these factors which have great influence on the performance.1. IntroductionThis part mainly introduces the current domestic and international situation of the piezoelectric technology and the existing problems and progress and the structural characters and working principles and the trend of the development of piezoelectric pumps.2. Theoretical Analysis on the Vibration Piezoelectric DiskThe piezoelectric disk, which is the source of power of a piezoelectric pump, is responsible for transforming electric energy into mechanic energy. It can deform when it is applied a proper voltage and frequency and the magnitude of the deformation has a direct influence on the working performance of a piezoelectric pump. A piezoelectric disk, which is usually comprised of piezoelectric and elastic materials in a specific way, utilizes the reverse piezoelectric effect to transform the electric signal into physical displacement or deformation so as to generate vibration.This part introduces the basic physical characters of piezoelectric disks and some of the important elements that have great influences on the working performance of a piezoelectric pump, including relative dielectric constant, elastic constants, electrical and mechanical coupling coefficient, mechanical quality factor, piezoelectric constant, working condition and constant frequency. The support way, resonant characteristics, vibration way of piezoelectric disk were studied. The static and dynamic states of piezoelectric disk were analyzed. And the LE modal, TE modal, FS modal, and TS modal of a piezoelectric disk are analyzed. According to the theory of thin board vibration, the modal of combined piezoelectric disk is analyzed and geometric formulation is proposed, including the Rayleigh-Ritz formulation.3. Experiment on the Combined Piezoelectric DiskIn order to have a better understanding of the vibration and performance of a piezoelectric pump, the displacement of deformation of the central line of the piezoelectric disk is tested under the loaded and unloaded circumstances. In addition, the central displacement is analyzed and compared.Conclusions drawn from the experiment are: the displacement of a piezoelectric disk is in a linear relationship with the voltage, and the displacement increases when the voltage increases. The displacement is also affected by the frequency. When the pump is loaded the central displacement is less than half as much as that when the pump is unloaded. The displacement of the central point decreases when the frequency increases.4. Analysis on the performance of a Piezoelectric PumpWith the help of the theory of dynamic fluid, the influence that may be imposed by the structure is analyzed theoretically. Some basic conceptions are introduced and the inner situation of the piezoelectric is analyzed as well as the head loss. The working principle and performance are analyzed and some of the key elements that have influences on the performance of the pump are also analyzed. The inner flowing situation is modeled numerically and analyzed.5. Models with chambers of different heights, with holes with different diameters and so on and a series of experiments are done to find out the law between the key factors and the performance.6. Summary of the main conclusions of the paper and prospects are made.