Abstract
In this paper, we investigate the idea of using, in place of recent linear force motors, amplified piezo-stack actuators for the actuation of direct drive servovalves, in order to exploit the fast response of piezoelements accompanied by the increased displacement ensured by mechanical amplification systems. Some possible architectures are proposed in this paper for the direct actuation of four-way three-position (4/3) servovalves using one or two commercially available amplified piezo-stack actuators having a diamond amplification mechanism. The simplest architecture, which employs only one actuator, is assessed using wellestablished equations implemented in Simulink, allowing the hydraulic, mechanical and electrical parts of the valve to be accurately simulated. Three spools of different size are considered in the simulations in order to obtain performance predictions for different valve flow ratings. From the analysis of the inherent characteristics of the amplified piezo-stack and from the results of the simulations, advantages and disadvantages of this possible architecture are drawn and discussed in detail. Among the advantages, there are the simplicity of construction and the high potential in terms of step response speed and frequency response; the large dimensions, low chip shear force capability and high costs are the main disadvantages.
Highlights
Servovalves are widely used components in several industrial and aeronautical applications
Such a single stage architecture, which is a servovalve because it has a bushing sleeve and is manufactured with fine tolerances, has the disadvantage of having lower actuation forces than two stage servovalves, lower chip shear capability and lower response speed [2]
This paper investigates how a single stage servovalve can directly be driven by piezoelectric actuators instead of linear force motors
Summary
Servovalves are widely used components in several industrial and aeronautical applications. The pilot stage, which usually employs a double nozzle flapper, a deflector jet or a jet pipe, is driven by a torque motor, providing hydraulic amplification for the main stage, which is usually a spool valve composed of a spool and a bushing sleeve This architecture provides several benefits, such as very high actuation forces and fast response speed [1]. The concept can benefit from novel and effective amplification mechanisms recently realized by some manufacturers, such as the “diamond” structure [13] In this scenario, a feasibility study of direct drive servovalves actuated by commercially available amplified piezo-stacks having diamond amplification mechanisms is performed for the first time in the present work. Advantages and disadvantages of this architecture, deduced by the simulation results and by the analysis of the characteristics of the amplified piezo-stack, are discussed in detail
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