Design and development of a flexurally amplified piezoelectric actuator based piezo-hydraulic pump

Abstract

Piezo-actuators can produce higher force and can be operated at higher actuation frequencies. However, the displacement range is limited to 0.1% of the actuator length. Piezo-hydraulic pumps developed using such piezo-actuators has to be operated at higher actuation frequencies to deliver higher pump flowrate. This limits the application of such piezo pumps for pumping higher viscosity fluids at higher flowrate. Thus, it is necessary to increase the displacement of piezo-actuators by different amplification mechanisms compromising with its maximum force handling capacity. Literature shows different piezo-actuator based piezo-hydraulic pumps, but piezo-hydraulic pump using flexurally amplified piezoelectric actuator is least reported anywhere. Hence, this work aims at development of a flexurally amplified piezoelectric actuator (FAPA) based piezo-hydraulic pump. The design of piezo-hydraulic pump consists of FAPA376 as pumping actuator and the pumping chamber is made from stainless steel metallic bellows. The inlet and outlet ports coming out from pumping chamber are connected with two unidirectional valves to avoid back flow of the fluid. The pumping actuator FAPA376 produces a maximum displacement of 376 µm when applied with its rated voltage signal of 150 V and hence by the name FAPA376. Suitable mathematical model for piezo-hydraulic pump is developed using MATLAB/Simulink software and simulations are carried out to determine pumping displacement and flowrate of the piezo-hydraulic pump. Simulation resulted with pumping peak displacement of 375.5 µm, hysteresis of 27.17 µm and flowrate of 25.55 mL/min at 1 Hz actuation frequency. Experiments are performed on developed piezo-hydraulic pump at different actuation frequencies to determine its pumping displacement and flow rate. Experiments carried out on the piezo-hydraulic pump at 1 Hz actuation frequency resulted with pumping peak displacement of 369 µm, hysteresis of 16.22 µm and flowrate of 25.36 mL/min. The simulated and experimental flowrate of piezo-hydraulic pump are in good agreement with each other having an error of 0.75% at 1 Hz.