Research On Piezohydraulic Step Actuator Driven By Multi-chamber Piezomembrane Pump

Several types of piezoelectric linear motors were developed and applied to the fields ofoptcal semiconductors and machining industries. The the output performanceof piezoelectric actuators is relatively low, so that the range of applications is subject torestrictions.The piezoelectric actuators unable to meet the workplace requires largedisplacements and high driving force. Integrated the superiority of piezoelectric actuationand hydraulic transmission, a new type of piezohydraulic actuator is designed in this paper.The piezohydraulic actuator has the advantage over the conventional contact/non-contactpiezoelectric motors in terms of achieving large thrust, high velocity, and long travelingdistance. With bimorph piezomembrane pump as the power, water as the energy transfermedium, hydraulic cylinder as the power output terminal, the actuator completes theconversion of micro-displacement to macroscopic motion and electrical energy tomechanical energy by the way of step drive. The paper includes:1. The article analyzed the structure and working principle of the piezohydraulicactuato. Aanalyzed the selection principle of component. Parsed the benefits of loaded backpressure in system. It lower the impact pressure of pump chamber in the course of theirwork, enhance the output performance of piezoelectric actuator. In addition, it reducethe occurrence of cavitation which protecte the piezoelectric pump and extend its workinglife.2. Established a mathematical model of the bimorph piezoelectric vibrator, studied theeffects of structure of piezoelectric oscillator, drive voltage and frequency to deformation ofthe piezoelectric oscillator.We found the radius ratio of ceramic and substrate and drivevoltage is proportional to deformation of the piezoelectric vibrator, thickness of the ceramicand substrate is inversely proportional to deformation of the piezoelectric vibrator.3. The parameters related to performance of piezohydraulic actuator was analysed andoptimized. Analysed the advantages and disadvantages of the different checked valves andadopted the rubble valve at last. And analysed the hysteresis of rubble valve. The positionof valve hole, the diameter of valve-orifice and calculating formulas of the chamber’sheight were deduced.4. According to the selected parameters, the piezohydraulic actuator driven bypiezomembrane pump was fabricated. Studied the oretical research and experimental testfor property.The test for property was conducted when piezomembrane pump was series-wound andparallel. Simultaneously, the results were obtained when the number of workingpiezomembrane is n (n=3-5) under the condition of parallel piezomembrane pump. A last, tested the impact of operating voltage.Loaded different back pressure and liquid which contains different amount of gas tothe actuator, then tested its performance.We got the affect of different back pressure andamount of gas to the performance of actuator, amount of gas to back pressure. The resultsshowed that: the appropriate back pressure can effectively improve the output performanceof actuator; the greater gas content in the fluid, the greater best load back pressure.Tested the impact of external load under the condition of the best back pressure.With the external load increases, the output speed and step length decrease. When the loadis lower than the best outside load, the output power of actuator is increase as the loadincreases. When the load is higher than the best outside load, the output power of actuatordecrease as the load increases.