Theoretical And Experimental Research Of Piezoelectric Pump Based On Inertia Principle

This paper is based on the National Natural Science Foundation Project "Piezoelectric drive fluid coupled software driver design Theory"(Item No.51405189).Aiming at the problem of large flow resistance and energy loss of traditional check valve,a kind of bionic valve with heart valve is designed,and when the bionic valve is opened,the disc is on the side of the runner,and the flow resistance and energy loss of the fluid are smaller.Based on the bionic valve,an inertial piezoelectric pump is proposed.The pump is driven by a piezoelectric cantilever beam,and the cantilever beam drives the vibration tube to vibrate up and down.The fluid is driven by the principle of inertia,so that the fluid flows upwards along the vibration tube under the action of the inertia force,and the pumping function is realized.The concrete research work of this paper is as follows:The theoretical model of piezoelectric cantilever beam is established,and the differential equation of output displacement and output force with voltage of cantilever beam is deduced according to Bernoulli-Euler theory formula.The modal analysis of piezoelectric cantilever is carried out,the first-order mode is the optimal mode,and the natural frequency under the mode is 30 Hz.The maximum displacement of the cantilever beam at 60 V voltage is 3.5mm by harmonic response analysis.The three main parameters(the position of the piezoelectric ceramic,the length and the thickness of the substrate)which affect the output displacement of the piezoelectric cantilever beam are simulated and analyzed.The simulation results show that the amplitude of the free end of the piezoelectric cantilever beam decreases with the increase of the distance between the fixed ends of the piezoelectric ceramic.At the fixed end of the piezoelectric ceramic,the maximum amplitude of the free end is increased gradually,as the length of the substrate increases,the thickness of the metal substrate increases first and then decreases.When the thickness of the metal substrate is 0.4mm,the amplitude of the free end is maximum.A kind of bionic valve with heart valve was designed,and the flow characteristic equation was deduced.A bionic valve simulation model with 0 °,15 °,30 °,45 °,60 ° and 75 ° is established.Under the condition that the inlet pressure is 30 Pa and the outlet pressure is 0Pa,the flow volume of the bionic valve is analyzed for a period of time,and the over-current characteristic of the bionic valve is optimal when the tilt angle is 60 °.At the same time,the movement trajectory of the disc in the opening process was obtained by the displacement probe,and it was found that the disc response was slow when the seat tilt angle was greater than 45 °.Then the experiment explored the output performance of the piezoelectric pump with different seat tilt angles when the valve bore diameter was 6mm.The experimental results show that the output performance of the piezoelectric pump is optimal when the seat tilt angle is 45 °.The optimal tilt angle is less than the simulation result,the reason is: when the seat tilt angle is more than 45 °,the valve opens the lag,causes the output flow of the piezoelectric pump to decrease with the seat inclination angle increases.Finally,the valve seat tilt angle of 45 °,different valve hole diameter of the piezoelectric pump was tested.This paper designs an inertial driving principle bionic valve piezoelectric pump,establishes the dynamic model of the piezoelectric pump,analyzes its pumping mechanism and deduces the output performance equation of the piezoelectric pump.The influence of the cantilever beam length and the free end mass on the vibration characteristics of the piezoelectric cantilever beam is investigated experimentally.The experimental results show that the the amplitude of the free end of the piezoelectric cantilever beam increases gradually with the increase of the length,and decreases with the increase of the additional mass at the free end,and the vibration tube is immersed into the liquid when the additional mass is compared with the fluid resistance of the vibrating tube.The maximum amplitude of cantilever beam decreases obviously,and the natural frequency changes less.The experimental platform is built to test the output performance of the inertial piezoelectric pump.Firstly,the influence of the length of piezoelectric cantilever beam on the output flow of the piezoelectric pump is discussed,and the output performance of the piezoelectric pump with the minimum cantilever length of 80 mm is optimized,and the piezoelectric cantilever beam of the length is selected as the driving element of the subsequent experiment.Secondly,in the case of the constant length of the vibrating tube,the influence of the height of the bionic valve distance and the immersion depth of the vibrating tube on the output performance of the piezoelectric pump is discussed,and the results show that the influence of the height of the bionic valve distance on the output flow of the piezoelectric pump is not obvious,and the output flow increases with the increasing of the immersion depth.Finally,in the case of changing the length of the vibrating tube,the effects of the working back pressure and the immersed depth of the vibrating tube on the output performance of the piezoelectric pump are tested experimentally.It is found that the maximum output flow of the piezoelectric pump is 228ml/min under the excitation signal of the voltage 98 V and the frequency 40 Hz when the vibrating tube length is 80 mm and the immersion depth is 20 mm.The above research shows that the bionic valve designed in this paper has the characteristics of reducing flow resistance and reducing energy loss,applying the bionic valve to the piezoelectric pump and verifying the feasibility of the inertia principle driving fluid.