Design, Analysis, Fabrication, and Testing of a Novel Piezoelectric Pump

摘要

While there is a wide range of actuation technologies, none currently rivals the overall performance (power density, bandwidth, stress, stroke) of conventional hydraulic actuation. It is well known in the actuation community that the power-to-weight ratios and the power-to-volume ratios of hydraulic actuators are, respectively, around 5 times and 10 to 20 times larger than comparable electric motors. Due to fundamental limitations in the magnetic flux density in the supporting structures and limitations in the heat transfer out of electric actuators, significant changes in these ratios are not likely in the near future. Thermal limitations associated with electric motors do no apply to hydraulic actuators since the hydraulic fluid cools and lubricates the system. Hydraulic actuators are capable of holding a load without any energy expenditure, resilient to high impact loads, and typically do no need a transmission system. However, with all of these virtues, hydraulic actuators have serious practical implementation problems. Typically, hydraulic actuators have moderate to poor reliability when compared to electric actuators, leaky (at least in reputation), poor energy efficiencies and poor controllability due to either overlapping or underlapping in the spool of the control valves. This work addresses a new type of electric actuator that attempts to combine the best of both the electric and hydraulic mediums. Easy controllability as with electric actuators, scalability, and high power densities associated with hydraulics were the goals of this work.