Project

Marie Curie Individual Fellowship-Development of a novel servovalve concept for aircraft (supported by the European Commission, EC Grant Agreement n. 701336)

Goal: This research project has been supported by the European Commission under the Marie Curie Intra-European fellowship Programme (EC Grant Agreement n. 701336, H2020 MSCA Individual Fellowship: Development of a novel servovalve concept for aircraft (DNSVCFA). Start date: 01/09/2017, End date: 19/10/2019, Location of the project: University of Bath).
The aim has been to develop a novel servovalve concept capable of overcoming the drawbacks of commonly used two-stage servo-valves. These valves are widely used in aerospace and industrial sectors because of their reliability and high performance in terms of step response speed and frequency response. However, they present a few disadvantages that are still unsolved at the state of the art. One of these disadvantages is the necessity for the pilot stage to have a quiescent flow rate to work: this internal leakage causes power consumption. Another disadvantage is given by the electromagnetic torque motor assembly, which is necessary to generate the hydraulic amplification, because it is composed of a large number of mechanical and electrical parts that penalize simplicity, set-up, and manufacturing costs .
The proposed architecture is capable of overcoming all these drawbacks by employing a novel solution for the pilot stage. The architecture proposed is based on the use of two small piezo-valves which have the task of changing the pressure at the extremities of a main spool. The piezo valves are two way two position (2/2) valves which are both actuated by a piezoelectric actuator. Each valve is hydraulically connected both to one of the extremities of a main spool and to one of two fixed orifices, which in turn are connected with the high pressure port P. The main spool can be a typical main spool of a four way three position (4/3) main stage valve. The sliding spool is moved directly by opening the left piezovalve or the right piezovalve depending on the required hydraulic connections (P-A and B-T, or P-B and A-T).This architecture can provide the following advantages compared to a typical two stage valve:
1. The two piezo valves are normally closed, therefore there is no internal flow through the small piezo valves when they are closed, which results in a notable reduction of the internal leakage through the system.
2. The implementation of small piezo valves has the potential to improve the response time of the main stage, because of the high dynamics of piezo-actuators, the low inertia of the components of the small piezo valves and the possibility of using control systems that act on both piezovalves simultaneously.
3. The need for a torque motor pilot stage with its associated disadvantages is also avoided.
The novel valve concept has been investigated using numerical approaches and experimental activities. The results are reported in the papers attached to this project.

Date: 1 September 2017

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Project log

Paolo Tamburrano
added a research item
This paper reviews the state of the art of directly driven proportional directional hydraulic spool valves, which are widely used hydraulic components in the industrial and transportation sectors. First, the construction and performance of commercially available units are discussed, together with simple models of the main characteristics. The review of published research focuses on two key areas: investigations that analyze and optimize valves from a fluid dynamic point of view, and then studies on spool position control systems. Mathematical modeling is a very active area of research, including computational fluid dynamics (CFD) for spool geometry optimization, and dynamic spool actuation and motion modeling to inform controller design. Drawbacks and advantages of new designs and concepts are described in the paper.
Paolo Tamburrano
added 4 research items
This paper proposes a novel architecture for the pilot stage of electro-hydraulic two-stage servovalves that does not need a quiescent flow and a torque motor as well as a flexure tube to operate. The architecture consists of two small piezoelectric valves, coupled with two fixed orifices, which allow variation of the differential pressure at the main stage spool extremities in order to move it with high response speed and accuracy. Each piezoelectric valve is actuated by a piezoelectric ring bender, which exhibits much greater displacement than a stack actuator of the same mass, and greater force than a rectangular bender. The concept is intended to reduce the influence of piezoelectric hysteresis. In order to assess the validity of the proposed configuration and its controller in terms of spool positioning accuracy and dynamic response, detailed simulations are performed by using the software Simscape Fluids. At 50% amplitude the −90° bandwidth is about 150Hz.
This paper provides a review of the state of the art of electro-hydraulic servovalves, which are widely used valves in industrial applications and aerospace, being key components for closed loop electrohydraulic motion control systems. The paper discusses their operating principles and the analytical models used to study these valves. Commercially available units are also analysed in detail, reporting the performance levels achieved by current servovalves in addition to discussing their advantages and drawbacks. A detailed analysis of research that investigates these valves via computational fluid dynamic analysis is also provided. Research studies on novel control systems and novel configurations based on the use of smart materials, which aim to improve performance or reduce cost, are also analysed in detail.
This paper provides a review of the state of the art of electro-hydraulic servovalves, which are widely used valves in industrial applications and aerospace, being key components for closed-loop electro-hydraulic motion control systems. The paper discusses their operating principles and the analytical models used to study these valves. Commercially available units are also analysed in detail, reporting the performance levels achieved by current servovalves in addition to discussing their advantages and drawbacks. A detailed analysis of research that investigates these valves via computational fluid-dynamic analysis is also provided. Research studies on novel control systems and novel configurations based on the use of smart materials, which aim to improve performance or reduce cost, are also analysed in detail.
Paolo Tamburrano
added a project goal
This research project has been supported by the European Commission under the Marie Curie Intra-European fellowship Programme (EC Grant Agreement n. 701336, H2020 MSCA Individual Fellowship: Development of a novel servovalve concept for aircraft (DNSVCFA). Start date: 01/09/2017, End date: 19/10/2019, Location of the project: University of Bath).
The aim has been to develop a novel servovalve concept capable of overcoming the drawbacks of commonly used two-stage servo-valves. These valves are widely used in aerospace and industrial sectors because of their reliability and high performance in terms of step response speed and frequency response. However, they present a few disadvantages that are still unsolved at the state of the art. One of these disadvantages is the necessity for the pilot stage to have a quiescent flow rate to work: this internal leakage causes power consumption. Another disadvantage is given by the electromagnetic torque motor assembly, which is necessary to generate the hydraulic amplification, because it is composed of a large number of mechanical and electrical parts that penalize simplicity, set-up, and manufacturing costs .
The proposed architecture is capable of overcoming all these drawbacks by employing a novel solution for the pilot stage. The architecture proposed is based on the use of two small piezo-valves which have the task of changing the pressure at the extremities of a main spool. The piezo valves are two way two position (2/2) valves which are both actuated by a piezoelectric actuator. Each valve is hydraulically connected both to one of the extremities of a main spool and to one of two fixed orifices, which in turn are connected with the high pressure port P. The main spool can be a typical main spool of a four way three position (4/3) main stage valve. The sliding spool is moved directly by opening the left piezovalve or the right piezovalve depending on the required hydraulic connections (P-A and B-T, or P-B and A-T).This architecture can provide the following advantages compared to a typical two stage valve:
1. The two piezo valves are normally closed, therefore there is no internal flow through the small piezo valves when they are closed, which results in a notable reduction of the internal leakage through the system.
2. The implementation of small piezo valves has the potential to improve the response time of the main stage, because of the high dynamics of piezo-actuators, the low inertia of the components of the small piezo valves and the possibility of using control systems that act on both piezovalves simultaneously.
3. The need for a torque motor pilot stage with its associated disadvantages is also avoided.
The novel valve concept has been investigated using numerical approaches and experimental activities. The results are reported in the papers attached to this project.