Theoretical And Applied Research On Piezoelectric Pump With Cantilever Valve

Title: Theoretical and Applied Research of Piezoelectric Pump with Cantilever Valve1.Introduction The piezoelectric pump is a new-type PZT driven device. Vibration producedby the piezoelectric bimorph (PZT actuator) acting on the fluid and producingpressure or flux output. It is an important part and researching focus in microflowsystems. There are more than ten counties and regions all over the world in whichthere are the research institutions of the piezoelectric pump. With many merits suchas simple structure, small body, no interfere of electromagnetism and good outputability under low applied voltage etc, the piezoelectric pump has very extensiveapplication prospects in the fields of chemical analysis, medical treatment,pharmacy and bioengineering etc. In order to meet the demand of the research item of national nature sciencefund and national advanced science plan(863) , this paper presents mainly someresearch on PZT pump with beam valve, PZT pump with two chambers and relatedtechniques using PZT pumps in CPU cooling.2. Theory analysis on the oscillating of piezoelectric bimorph Piezoelectric bimorph is the power source to the piezoelectric pump, whichplay the key role on transforming the electric energy into mechanical energy. Thesimplest bimorph is made by bonding a piezoelectric element to one side of apassive elastic plate. It makes use of the piezoelectric material's reversepiezoelectric effect to transform the electric signal into the machine displacement,and engender oscillating of the whole piezoelectric bimorph. On the basis of the knowledge that relates to piezoelectric effect, piezoelectricmaterials and their performance parameters, we analyze the oscillating mode to thepiezoelectric bimorph composed of single piezoelectric ceramic plate and metalsheet, educed the geometry equation and constitutive equation of piezoelectricbimorph. The vibration rule of PZT bimorph with different valve sheets and valve holesis observed. During function, we know the width of valve sheet has littleinfluence to bimorph vibration swing, but the length of valve sheet has greatinfluence to its vibration swing and the frequency related to the optical vibrationswing. The flux of PZT pump increases with the augment of valve hole's diameter. Analysis to the edge-fixed PZT bimorph with Impedance Analysis Equipmentshows after priming the frequency of PZT pump bimorph decreases apparently, butmuch more than optical frequency in practical work. The deformation of PZT bimorph is in direct proportion to the applied voltage.It increases when the applied voltage augments. At the same time, it is also affectedby the input signals, sine wave the biggest, triangle wave bigger and rectangularwave the smallest.3. The theoretical analysis and experimental research of single-chamberedPZT pump with beam valve According to the working environment of beam valve sheet in PZT pump, itsdynamic model is fabricated and the base frequency calculating method of beamvalve in liquid and the relations between every structural parameter are presented,providing theoretical warrant for the design of beam valve. The PZT pump's output ability and optical working frequency are related withthe diameter of valve hole. The bigger is the diameter of valve hole, the greater isthe output flux, the higher is the optical working frequency. Valve is another main element which affects the PZT pump's performance.Lengthening the valve sheet, leading to the increment of system impedance, lowersthe output ability and optical working frequency of PZT pump. When valve'sresonance frequency is closed to the resonance frequency of PZT bimorph, systemwill resonate. So the optical working frequency of PZT pump is got. Widening thevalve sheet, leading to the increment of system impedance and improvement ofclose ability, has little influence to the output ability.4. The analysis and experiment on the use of PZT pu...