Study On Diaphragm Pump Based On Rectangular Piezoelectric Vibrator Through An Indirect-driven Way

With the development of MEMS technology, piezoelectric pump has beenwidely studied and applied to, due to its simple structure, easy miniaturization andother characteristics.The piezoelectric diaphragm pump is a typical piezoelectricpump. Researchers have been optimizing the design and manufacture of thediaphragm pump so that its stability and output performance improvescontinuously.The diaphragm pump is widely used in industry fields, but specialapplications put forward higher requirements to piezoelectric pump’s dimensionsand output performance.This paper is based on the National Natural Science Fund Project of “TheStudy of Theory and Key Technology on Piezoelectric Gas Diaphragm”. On onehand,it refers to the results from the previous study of using the resonance theory toimprove output performance for diaphragm. On the other hand, thick rectangularpiezoelectric ceramic is used to produce piezoelectric vibrator to improve the inputpower so that the structure of the vibration systemis simplified--the piezoelectricvibrator drive the pump chamber diaphragm directly through the vibrationtransmission part.In this study, rectangular piezoelectric vibrator of the holder fixed at bothendsis made according to rectangular lateral vibration modes of the piezoelectricceramic. Based on Ansys piezoelectric coupling field, the author analyzespiezoelectric vibrator vibration modes. The elastic substrates at the both ends ofvibrator have large deformation because of small stiffness,the center part ofpiezoelectric bonding ceramic have small deformation because of the large stiffness. The experiment studies the relationship between the driving voltage by the operatingfrequency and the rectangular center of the piezoelectric transducer displacementoutput, the rectangular output characteristic data about the displacement of thepiezoelectric vibrator.The pump chamber structure has a direct impact on the output pressure andflow rate of piezoelectric pump.Both decreasing the cross-sectional area andincreasing the changing rate of the cavity volume helps to improve the outputpressure of diaphragm pump. Use shell theory to analysis and calculation thedeflection of diaphragm pump’s diaphragm under the condition of no load. Matlabare used to calculate the volume change of the pump cavity. Get the relation curve ofpump cavity volume variation and the structure of elastic wafer. The experiment of arelationship between the output performance of pump and the diaphragm stiffnessproves the result that diaphragm of smaller stiffness has large amplitude under thecondition of the same driver and has a good performance in terms of output flow andpressure.In order to reduce energy consumption of the valve during the working processof the diaphragm pump and to simplify the overall structure, this paper selects thecantilever valve. Build the vibration model of the cantilever valve and analyze thevalve’s opening degree. Valve movement is similar to the vibration of single degreeof freedom system under harmonic excitation.There is a specific natural frequencylet the valve opening degree reach the maximum. Study the relations of outputperformance of diaphragm pump and the best response frequency of cantilever valvethrough the experiment. Find the best match of the two, and improve the outputperformance of diaphragm pump.After setting up a vibration model of the system diaphragm and analyzing theresonant frequency of computing system, we aim to develop adiaphragm prototypewith lower resonant frequency, by adjusting the mass and stiffness of the vibrationsystem.To test the performance of the diaphragm pump for pumping gas in theIV condition of resonance,the results show an important phenomenon:the amplitude ofthe diaphragm is continuously decline near the best response frequency of thecantilever valve, while the output flow and pressure of diaphragm pump arerising.This suggests that we should not ignore the best working frequency of thevalve affecting the performance of the pump. We should adjust the resonancefrequency of the diaphragm pump or the best response frequency of the valve further,making the two nearly equal, to improve the output performance of the diaphragmpump.