Mathematical modelling and experimental characterization of a high dynamic servo valve integrated with piezoelectric actuator

Abstract

A conventional two-stage servo valve basically consists of an electrically operated torque motor as the first stage and spool valve as the second stage. Owing to the limitation in the band width, servo valves are not suitable for high-frequency applications. The work presented in this paper deals with the methodology of the mechatronics approach for the design of a piezoelectric actuator with a mechanical amplifier and its integration into a servo valve. The analysis and simulation of a multilayer piezoelectric actuator (MLA) a with mechanical amplifier for high-frequency application has been done using icon-based bond graph technique and finite element coupled field analysis for the commercially available piezoelectric actuator. The designed piezoelectric actuator was integrated into an existing flapper-nozzle servo valve by replacing the first stage. The dynamics of the valve integrated into a piezoelectric actuator has been simulated. The required simulation parameters for the actuator have been derived from a finite element model. An experimental set-up has been designed and the integrated testing of the servo valve with piezoelectric actuator has been carried out to determine the no-load flow gain of the valve. Also the time response has been measured for a conventional servo valve and servo valve with piezoelectric actuator. The designed valve with a piezoelectric actuator has satisfactory static and dynamic characteristics for high-speed applications.

A Novel Servovalve Pilot Stage Actuated by a Piezo-electric Ring Bender: A Numerical and Experimental Analysis

“…Another adjustable mechanical stop (15) is also employed in order to allow the maximum displacement of the ring bender (i.e., the maximum opening of the valve) to be regulated. The pressure of the oil discharged from the piezo-valve is measured by a pressure transducer (16).…”

“…The picture of the test rig ( Figure 3b) shows the pressure transducer (5), the variable restrictor (6), the pressure transducer (7), the valve case (8), the adjusters (9) and (15) and the pressure transducer (16). (model CMBR07) were purchased from the manufacturer Noliac [29].…”

“…In particular, a promising research field aims to replace the electromagnetic torque motor assembly with piezoelectric actuators, thus reducing complexity and manufacturing costs [2]. Different types of piezoelectric actuators have been used to directly drive the main stage spool or to drive the flapper, jet pipe or deflector jet in the pilot stage [11][12][13][14][15][16][17][18][19][20][21], showing that the idea of using a piezo-electric actuator to drive a servovalve is feasible and promising. One of the commercially available piezoelectric actuators that has been used for this purpose is the stack-type, in which several piezo elements are joined together to form a multi-layer actuator [11][12][13]; in parallel to piezo-stacks actuators, also amplified piezo-stack actuators, which can provide higher displacement but lower forces, have been proposed to replace the torque motors in servovalves [14][15][16].…”

Non-linear control of a hydraulic piezo-valve using a generalised Prandtl–Ishlinskii hysteresis model

“…Sedziak et al [14] investigated a servovalve with barometric feedback where the ferroelectric hysteresis of the piezoelectric had a significant influence on the valve flow characteristics. In [17] the authors presented a servovalve where a piezoelectric stack actuator moved a flapper assembly and the displacement of the piezoelectric stack was mechanically amplified. The influence of ferroelectric hysteresis can also be observed in the response of the flow rate versus input voltage.…”

High Precise Fuzzy Control for Piezoelectric Direct Drive Electro-Hydraulic Servo Valve

“…Due to the piezoelectric actuator (1)- (3) has the advantages of fast response, easy control and high control accuracy, it can be used as the electric-mechanical converter of electro-hydraulic servo valve (4)- (8) . However, the main drawback of the piezoelectric actuator is that there are large hysteresis loops (9)- (11) (up to 15%) between the input voltage and the output displacement.…”