| 1,IntroduceThis part gives us a mainly introduction to the piezoelectric-pump about home and abroad,and expatiates the characteristics and the working principles,and analyses the development trend.The piezoelectric-pump driven by piezoelectric-stack is a newly development trend,it can accommodate pressure in a large scale and control the output flux in precision.This pump will widely apply to transfusion,feed oil and clean the equipment in industrial automation,and scientific research,lab, chemical preparation and cooling of CPU etc.2,The basic principle of piezoelectric Actuation technologyBecause the piezoelectric-stack is the core part of the pump that we designed,we should pay more attention to driven principle of the piezo-stack so that we can using it correctly.This paper introduces piezoelectric material and interrelated parameter,output characteristic and driven principle and driving type of piezoelectric-stack.Piezoelectric-stack can give more output displacement and pressure and have more rate of conversion and more stability than bimorph type.These characteristics of piezoelectric stack help it can used to piezo-stack pump.3,The analytic method and FE method of rhombus hinge micro displacement amplifierWe design displacement amplifier because of the little displacement output of the piezo-stack.This paper analyses the disadvantage and advantage of all sorts of amplification,and proposes a type of displacement amplifier based on flexural gemel. The modeling study of the displacements amplifier, based on flexure hinges, was processed by analytic method and FE method. The statics and dynamics analysis of the mechanism was carried on, and got the conclusion that the output displacements were influenced by various structure parameters. The results were compared with analytical solutions and showed that the output displacements of flexure hinge is influenced by centre thickness t, thickness of the amplifier T,arc radius r, radianα, furthermore the output displacements is not influenced by width . The resonance frequency and vibration modes of the mechanism were resulted by FE method. Finally, the system dynamics parameter data from the analytic method and FE method was compared and analyzed.4,Structure Design of the Piezoelectric Stack Pump and Analysis of Hydraulic StateThe figure on the right shows the structure of piezoelectric-atack pump that we made,which makes up of pump-body,insulation film,displacement amplification,input and output valve.Because of the remote output of the displacement amplification,the assembly is very strict.Especially the connection of displacement amplification with the other part which must be pre-tightened.Analyse the advantages and disadvantages of the different checked valves and adopt the rubble valve at last in order to simpled the structure of the piezoelectric pump. Analyse the principle and lag phenomena of rubble valve. Discussed the pressure distributing law when outleting from axes and radial. And get the conclusion,the axes-way outlet is better to enhance the piezo pump output ability.The output pressure is higher when the output diameter minish.5,Test and Research on the Piezoelectric Stack Pump We design and fabricate the prototype of displacement amplifier and pump,and make a series of experiments.The displacement amplifier is made from spring steel.Because the material is good to store spring energy which can imprve the response of structure and reduce the lag.It is made by EDM machine.Before the machining,spring steel must be annealed,so that can eliminate vestige stress and improve the cutting performance.After the machining,the workpiece must be heat treated,so that have a good general mechanical performance.By the test of displacement amplifier ,it can be indicated that the displacement amplifier has better characteristics of statics and dynamics. And the results are confermed the veracity of FE method. In this paper, the test of pressure and flux were carried out. Analysis and test the influence of prototype output performance in different input signals and pumpbody parameters. In additional, get the piezo-stack pump output precision by testing.6,Conclusions1) Displacement amplifier based on the triangle amplification principle. To reduce the centre thickness t can enhance the output displacement; There is a maximum of output displacement around 4°, and further reduction of angleαcannot increase the output displacement.2) The output displacement of pre-stage driver is 50μm, the amplification is 5 times, and resonance frequency is 1500Hz. So the pre-stage has certain drive capability.3) The output pressure and flux(in zero pressure) of piezo-stack pump is fundamentally linear to input voltage, and the number of two parameters are increased with the increasment of voltage.What's more, piezo-stack pump is a kind of pump which is working at low frequency.4) Working performances of piezo-stack pump are influenced by input signal and parameters of pumpbody. When input signal is rectangle signal, the working performances(it indicate output pressure and flux) of piezo-stack pump is better than other signals. When the pump cubage is decreased in concent bound, the working performance of pump is increased. In addition, in concent bound the thicknees of vibrating membrane the better of pump working performance.The pump can work in a single pulse,and the minimum flux of single pulse is only 0.03ml. Suppose that the voltage are constant and implus number is not change, the result shows that the linear of flux is obvious.
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