A Review of Novel Architectures of Servovalves Driven by Piezoelectric Actuators

Abstract

This paper is a thorough review of innovative architectures of electro-hydraulic servovalves that exploit actuation systems based on piezo-electric materials. The use of commercially available piezo-electric actuators, namely, piezo stacks, amplified piezo stacks, rectangular benders, and ring benders, is very promising for the actuation of the main stages and of the pilot stages of servovalves given the fast response and low weight of piezoelectric materials. The use of these actuators can also allow novel designs to be developed, thus helping manufacturers to overcome the typical drawbacks of commercial servovalves, such as the high complexity and the high internal leakage of the pilot stages of two-stage servovalves as well as the large size and weight of direct-drive servovalves. First, the piezoelectric actuators that can be used for driving servovalves are presented in the paper, and their characteristics are thoroughly discussed. The main novel architectures present in the literature are then explained and compared with the commercial ones, and their performance parameters are discussed to draw conclusions on the prospect that some of these architectures can be used by manufacturers as future designs.

Claw‐pole magnetic levitation torque motor for 2D valve with automatic neutral adjustment

“…The parameters of the algorithm are set as: the population size is 300, the number of iterations is 300, the crossover probability is 0.9, and the mutation probability is 0.5. The parameter ranges are as follows: 4,9], x 4 ∈ [30, 38] and x 5 ∈ [13,15]. Figure 7a shows the Pareto front between F z maximisation and T m maximisation; Figure 7b shows the Pareto front between T c -1293 maximisation and F z maximisation; Figure 7c shows the Pareto front between T c maximisation and T m maximisation.…”

“…As control and adjustment elements, hydraulic valves are used to adjust oil pressure, flow or direction of oil flow and play a key role in the performance of the entire system. Structurally, almost all hydraulic valves are composed of spool, valve body and electromechanical converter that drives the movement of the spool [4,5]. Due to the limited output force of the electromechanical converter, the direct-acting hydraulic valve can only be used in low-pressure and small-flow scenarios.…”

Detailed simulations of an aircraft fuel system by means of Simulink

“…The two-stage servovalve, acting as the fuel metering valve, can be equipped with a centring spring for mechanical feedback or with a Linear Variable Differential Transformer (LVDT) sensor for electrical feedback [14]. This valve usually has high-performance levels; however, this key component is also a source of energy dissipation, essentially due to three main reasons: 1) internal leakage occurs in the main stage due both to the geometrical tolerances necessary to make the spool move and to geometrical imperfections [15][16][17]; 2) a pressure drop is generated because the fuel flows through the small passages of the main stage [14,17]; 3) even when the valve is at rest, the pilot stage continuously requires a quiescent flow to operate, which is taken from the pump and is then discharged into the tank [14,17].…”

Flow-reduced double valve actuation for improving the dynamic performance of electro-hydraulic servo drive

“…19 The servo valve driven by piezoelectric actuator possesses higher effective frequency than traditional servo valve. 20,21 However, the piezoelectric actuators have disadvantages of high hysteresis and sensitivity to creep, 22 which affect the accuracy of servo valve. Similarly, the servo valve driven by giant magnetostrictive actuator has the property of fast response.…”