Development of fast-actuation piezo systems for high-performance Fluid Power technologies

This PhD research project investigates the transformative potential of piezoelectric actuators in addressing the inherent limitations and problems of conventional hydraulic components, particularly focusing on valves and pumps. Despite the great advantages it offers, such as high-power density, precise control and large force output, conventional hydraulic technology suffers from low energy efficiency due to substantial energy losses that occur as the pressurized oil flows through the hydraulic circuit and its components, particularly the control-ones. Conventional hydraulic technology typically utilizes analogue spool valves, such as proportional and servovalves, as control components in various industrial and aeronautical applications where high precision and fast response are required. However, the spool design of these valves leads to high power dissipation, caused by the significant pressure drop across the small narrow passages uncovered during valve control. Moreover, the actuation system's architecture introduces additional drawbacks, such as increased complexity and higher manufacturing costs, which remain still unresolved. To explore these challenges, the research begins by developing comprehensive simulation models of aircraft fuel systems, specifically focusing on quantifying energy inefficiencies in servovalves within fuel metering units. Building on these insights, the first goal of the project is to design and model innovative spool valve architectures powered by piezoelectric actuators, replacing traditional electromagnetic actuators. By leveraging the fast response times and simplicity of piezoelectric materials, this approach aims to improve energy efficiency, reduce costs, and simplify the design of conventional spool valves. The project also explores the potential of digital hydraulics, which aims to replace conventional proportional and servovalves in industrial and aeronautical applications with low-cost, robust on/off valves in order to minimize power dissipation. However, the practical implementation of digital hydraulics is currently limited by challenges in manufacturing on/off valves that meet strict requirements, such as high switching frequencies and speeds (below 5 ms), minimal pressure losses, and the ability to handle large flow rates in a compact form. Once again, piezoelectric actuators could provide a crucial solution to these challenges. Thus, the second goal of this research is to design and model innovative high-frequency switching on/off valve architectures, marking digital hydraulics as a promising technology for improving energy efficiency in various fluid power applications. Lastly, this research addresses, as third goal, the growing demand for pumps in industries such as chemistry, biomedicine, aerospace, robotics, and liquid cooling. These fields require pumps that are compact, reliable, quiet, and capable of precise flow control—qualities that conventional hydraulic pumps often struggle to meet due to inherent structural limitations. Specifically, the research project explores the use over again of piezoelectric actuators to design, develop and testing innovative precision fluid pumps that can meet these stringent requirements, aiming to expand the power capabilities of this innovative technology.