Design And Experimental Study Of Piezoelectric Resonant Pump Based On The Flexible Support

The piezoelectric diaphragm pump has high precision and quick response in liquid delivery.It has a broad application market,because its structure is compact and easy to be miniaturized.The traditional piezoelectric diaphragm pump drives the fluid directly through the piezoelectric vibrator.The surrounding of the piezoelectric vibrator is fixed on the pump body,which restricts the vibration of the vibrator.It is difficult for piezoelectric diaphragm pump to obtain large volume change of the pump chamber.The application of resonance principle provides a solution to increase the volume change of pump chamber.The resonant piezoelectric diaphragm pump separates the piezoelectric actuator from the pump chamber diaphragm.According to the resonance theory,the displacement of the actuator is amplified so as to drive the diaphragm.Foreign researchers used piezoelectric stacks as actuators when designing the resonant pump,in order to take the advantage of the large output force from the stacks.However,the manufacturing process of piezoelectric stack is complex.Meanwhile,piezoelectric stack is expensive and bulky.Domestic research on resonance pump started late,but is increasing gradually in recent years.These studied resonant pumps mainly use piezoelectric vibrators as actuators.This paper is based on the National Natural Science Fund Project of “The Study of Theory and Key Technology on Piezoelectric Gas Diaphragm”(NO.51175213).A piezoelectric resonant pump(hereinafter referred to as the "resonant pump")based on the flexible support is proposed.Using the principle of resonance,the vibration displacement of the square piezoelectric vibrator is amplified to drive the pump chamber diaphragm.The study is to explore the effective methods on increasing the flow rate and pressure of the piezoelectric diaphragm pump,and the long-term working stability as well.The main contents are as follows:1?Study on square piezoelectric vibrator for the resonant pumpThe deformability of the circular piezoelectric vibrator with fixed support is limited.In this paper,a novel square piezoelectric vibrator is presented.A square piezoelectric vibrator based on the flexible support is proposed.A fixed method of four corners is adopted to reduce vibration constraint of square piezoelectric vibrator.The stiffness calculation model of the square piezoelectric vibrator is established,and the static and dynamic output characteristics of the square piezoelectric vibrator are studied by finite element simulation to optimize the structure parameters.The static and dynamic output performance of the square piezoelectric vibrator is verified by testing the output displacement,output force and resonant frequency.2?Study on the wheel valve for the resonant pumpThe resonant pump works near a specific resonant frequency,and it is important to select a check valve that performs well at a given frequency.After analyzing different types of check valves,the resonant pump adopts wheel valve.The wheel valve collides with the pump during working process.The motion model of the wheel valve is established.According to the theory of plate gap flow,the theoretical flow of wheel valve is deduced.We get the relationship between the stiffness of the wheel valve,the working frequency and the flow rate by using Matlab.The effect of wheel stiffness on its working performance was studied by performance test.3?Modeling and analysis of the vibration systemThe vibration displacement of piezoelectric actuator is small,and it is difficult to obtain the ideal volume change of pump chamber.In this paper,the square piezoelectric vibrator is connected with the pump chamber diaphragm through the elastic drive mechanism.A two degrees of freedom vibration system is constructed for resonant pump.The dynamic model of resonant pump is established,and the vibration system is optimized by adjusting the mass and rigidity of the elastic drive mechanism.The amplitude frequency characteristics of resonant pump are studied by performance test.4?Experimental study on the resonant pump performanceAccording to the theoretical analysis,the resonant pumps prototypes are produced.And the structure parameters of resonant pump are optimized by performance test.The reasonable pump chamber and runner structures will affect the output performance of the resonant pump.The optimum pump chamber height of the resonant pump is found through the experiment.At the same time,the diversion trench and compressible chamber structures are applied to the resonant pump to improve its output performance.5?The study on optimizing the resonant pump by wall wettabilityWorking under resonance is the premise of high performance of resonant pump.Due to the large amplitude of the resonant pump,the liquid in the pump chamber can easily produce bubbles under the strong vibration of the pump chamber diaphragm.These bubbles can severely interfere with the stability of the resonance system.In order to reduce the damage of the bubbles,and to study the method of improving the stability of the resonant pump,this paper studies the interaction between the bubbles in the liquid and different wall surfaces.The wall wettability principle is applied to the runner system of the resonant pump.The effect of different wettability walls on the output performance of resonant pump was tested.Through the experiment,the method of controlling bubbles is found.