There are two kinds of piezoelectric pumps:check valve pumps and valve-less pumps.Whether to use a check valve or not depends upon the application occasion.To achieve large backpressure for higher flow rates,the pump with check valve is desirable.However,adding check valves implies more complex structure and higher probability of valve blocking,etc.In order to solve the problem,effective driving and transport mechanics with compact construction and reliable service are being sought.In this paper,using the second-order longitudinal vibration mode of a bar-shaped piezoelectric vibrator for driving fluid,a piezoelectric pump is successfully made.The proposed piezoelectric pump consists of coaxial cylindrical shells and a bar-shaped piezoelectric vibrator,which has a disk part and a cone part.The lead zirconium titanate ceramic rings fixed in the vibrator are polarized along the thickness direction.When the second-order longitudinal vibration of the vibrator along its axis is excited,the disk part of the vibrator changes periodically the volume of the chamber and the cone part acts as a pin valve,driving the fluid from the inlet port to the outlet port.Finite elements analysis on the proposed pump model is carried out to verify its operation principle and design by the commercial FEM software ANSYS.Components of the piezoelectric pump were manufactured,assembled,and tested for flow rate and backpressure to validate the concepts of the proposed pump and confirm the simulation results of modal and harmonic analyses.The test results show that the performance of the proposed piezoelectric pump is about 910 mL/min in flow rate with a highest pressure level of 1.5 kPa under 400 V peak-to-peak voltage and 51.7 kHz operating frequency.It is confirmed that this bar-shaped piezoelectric transducer can be effectively applied in fluid transferring mechanism of pump through this research.
