Large Flow-rate Piezoelectric Pump Powered By Centrally Clamped Actuator

Piezoelectric pump is powered by a piezoelectric material that poses inverse piezo-electric characteristic, when the piezoelectric vibrator is actuated by an AC voltage, its deformation causes the volume change of the pump chamber, resulting the differ-ence pressure between the inside and outside of the chamber, than the fluid is forced in and out the pump because of the different pressure. Owing to its outstanding features such as small size, low power consumption, easy to control and no magnetic influence, widespread concern has been paid to piezoelectric pumps, through a few years of de-velopment, they have been widely applied in drug delivery system, chemical analysis system, micro-electromechanical system, and aerospace and other fields. In the future, piezoelectric may have more application prospect.Conventional research on piezoelectric focus more on small and micropump, the advantage of these pumps is they have the ability to control the flow rate and out pressure precisely. However, some special situations require the compact pump to offer large flow rate, like the cooling system in the computer, bath mixing system of solvent and solute, heart assistant system. Different methods have been carried out to achieve large flow rate of the piezoelectric pump. In spite of the large flow rate, these pumps have disadvantages of high cost, complex structure and large sizes which are not suitable for the above-mentioned situation. In this paper, we use the most common and simple round bimorph composite piezoelectric disk to power the pump, and we achieved a compact and large flow-rate piezoelectric pump. Here we found a new way to support the vibrator which allowed the pump to get a larger flow rate than the traditional one. The size of the piezoelectric disk is Φ25 mm×0.2 mm, and the total size of the pump is 42 mm×42 mm×12mm. When the pump is actuated by a sinusoidal signal at 400 Vpp and 410 Hz. the pump can tap water at a flow rate of 1000 mL/min under zero backpressure, and achieves a pump pressure of 20 kPa at 800 Hz under zero flow rate.What we have done incudes:1、Compared different styles of the vibrators like piezoelectric stacks and piezo-electric plates, different piezoelectric material, different drive methods and discussed the disadvantages and advantages of them.2、Based on the thin plate flexure theory and combined the theory of the vibration, we built the functions to evaluate the maximum displacements of the vibrator support-ed by three different means, ie edge-clamped, edge-simply supported and center-fixed. Simulation analysis was also done to compare the displacements of the vibrators. Then we used the laser displacement sensor to measure the displacements of the vibrator sup- ported by three different means mentioned above. A digital impedance analyzer was used to obtain the admittance curves of the three vibrators. Than we used the MATLAB to calculate the volume change in a period of the vibration.Based on the theoretic de-duction and combined with the simulation software, we discussed the displacement of both different sizes of the PZT plates and the metal membranes.3、We designed a structure that the center of the vibrator was fixed by sticking it to a steel cylinder. To form a closed chamber and ensure the displacement of the edge of the vibrator at the same time, we designed a clearance between the edge of the vibrator and the edge of the chamber and there was a rubber connect the vibrator and the chamber, that meant the diameter of the chamber was a little larger than the diam-eter of the vibrator, and we had found that the existence of the rubber would decrease the displacement of the vibrator a little, and an analysis was also done to learn the in-fluence of different wides of the clearance on the displacement. To improve the stress distribution on the PZT, a gasket was introduced between the vibrator and the fixing cylinder. We made a pump which had a total size of 42 mm x 42mm x 12mm, and tested the performance of the pump, including influence of different rubbers, different valves and different gaskets on the flow rate of the pump. When the pump is actuated by a sinusoidal signal at 400 Vpp and 410 Hz, the pump can tap water at a flow rate of 1000 mL/min under zero backpressure, and achieve a pump pressure of 20 kPa at 800 Hz under zero flow rate.4、An experiment was done to compare the flow rate of the pumps that have dif-ferent ways to support the vibrator, and we also made a comparison with some previous studies.