Cet ouvrage fait partie de la bibliothèque YouScribe
Obtenez un accès à la bibliothèque pour le lire en ligne
En savoir plus

Development of high-response piezo-servovalves for improved performance of electrohydraulic cylinder drives [Elektronische Ressource] / Maxim Reichert

De
156 pages
Development of High-Response Piezo-Servovalves for Improved Performance of Electrohydraulic Cylinder Drives Von der Fakultät für Maschinenwesen der Rheinisch-Westfälischen Technischen Hochschule Aachen zur Erlangung des akademischen Grades eines Doktors der Ingenieurwissenschaften genehmigte Dissertation vorgelegt von Maxim Reichert Berichter: Univ.-Prof. Dr.-Ing. H. Murrenhoff Univ.-Prof. Dr.-Ing. D. Abel Tag der mündlichen Prüfung: 04.02.2010 Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verfügbar. WICHTIG: D 82 überprüfen !!!Reihe FluidtechnikBand 55Maxim ReichertDevelopment of High-Response Piezo-Servovalvesfor Improved Performance of ElectrohydraulicCylinder DrivesShaker VerlagAachen 2010Bibliographic information published by the Deutsche NationalbibliothekThe Deutsche Nationalbibliothek lists this publication in the DeutscheNationalbibliografie; detailed bibliographic data are available in the Internet athttp://dnb.d-nb.de.Zugl.: D 82 (Diss. RWTH Aachen University, 2010)Copyright Shaker Verlag 2010All rights reserved. No part of this publication may be reproduced, stored in aretrieval system, or transmitted, in any form or by any means, electronic,mechanical, photocopying, recording or otherwise, without the prior permissionof the publishers.Printed in Germany.
Voir plus Voir moins










Development of High-Response Piezo-Servovalves for
Improved Performance of Electrohydraulic Cylinder Drives



Von der Fakultät für Maschinenwesen der Rheinisch-Westfälischen Technischen Hochschule
Aachen zur Erlangung des akademischen Grades eines Doktors der Ingenieurwissenschaften
genehmigte Dissertation



vorgelegt von



Maxim Reichert
























Berichter: Univ.-Prof. Dr.-Ing. H. Murrenhoff
Univ.-Prof. Dr.-Ing. D. Abel

Tag der mündlichen Prüfung: 04.02.2010

Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verfügbar. WICHTIG: D 82 überprüfen !!!
Reihe Fluidtechnik
Band 55
Maxim Reichert
Development of High-Response Piezo-Servovalves
for Improved Performance of Electrohydraulic
Cylinder Drives
Shaker Verlag
Aachen 2010Bibliographic information published by the Deutsche Nationalbibliothek
The Deutsche Nationalbibliothek lists this publication in the Deutsche
Nationalbibliografie; detailed bibliographic data are available in the Internet at
http://dnb.d-nb.de.
Zugl.: D 82 (Diss. RWTH Aachen University, 2010)
Copyright Shaker Verlag 2010
All rights reserved. No part of this publication may be reproduced, stored in a
retrieval system, or transmitted, in any form or by any means, electronic,
mechanical, photocopying, recording or otherwise, without the prior permission
of the publishers.
Printed in Germany.
ISBN 978-3-8322-9278-2
ISSN 1437-8434
Shaker Verlag GmbH • P.O. BOX 101818 • D-52018 Aachen
Phone: 0049/2407/9596-0 • Telefax: 0049/2407/9596-9
Internet: www.shaker.de • e-mail: info@shaker.de




In memory of my beloved
Galina and Andrej Linkevich Preface
This book evolved during my work as a research assistant at the Institute for Fluid Power
Drives and Controls (IFAS), RWTH Aachen University, Germany. Starting from the exotic
electro-rheological fluids in my student project work, then, dealing with the use of
piezoelectric actuators in valves at the beginning of my research and, finally, considering
control improvements of electrohydraulic cylinder drives I have been always wondering
how diverse and interdisciplinary is the world of fluid power technology. It challenges the
researcher with many interesting tasks and requires profound theoretical knowledge
combined with a strong affinity for experimental work.
The thesis resulted not only from the carried out experiments but also from the inspiration
and enthusiasm, found at IFAS among my colleagues and students. I would like to thank
my doctoral advisor and the head of IFAS, Professor Murrenhoff, for his mentorship and
encouragement. I am obliged to Professor Abel – the head of the Institute of Automatic
Control – for a critical review of the thesis. And I appreciate the sense of humour of
Professor Schröder – the head of the Chair of Fluid Mechanics and Institute of
Aerodynamics – who guided the doctoral examination.
I am grateful to my colleagues – Torsten Kohmäscher, Matthias Liermann, Olivier
Reinertz, Kristof Schlemmer and Torsten Verkoyen – who had taken a look at this thesis
before it landed on Professor Murrenhoff’s desk. I will always keep in mind my roommates
with an extraordinary international background – Albert Schultz, Roberto Grassi,
Mohamed El-Ashmawy, Tapio Torikka, Timo Nafz and Nils Vatheuer – for a harmonic 10
2
hour-a-day coexistence in a 9 m -office. I am thankful to Michael Zaun and Christian
Stammen who inspired me for the hydraulics when I dropped in at IFAS as a student for
my project works. Finally, special thanks go to my own students – Christian Schleihs,
Christian Dornieden, Marcus Specks, Gregor Reitz, Thomas van Hengel, Sebastian Porth
and others – who supported my work and were inspired for the hydraulics as well.
Above all I would like to thank my family and my wife, Olga, who always supported me
and stood by my side in any situations.

th
Horgen, 20 of July, 2010 Maxim Reichert Abstract
This book deals with the development and testing of high-response piezo-servovalves for
improved performance of electrohydraulic cylinder drives. Performance improvement
means in the context of this work an enhancement of reference and disturbance response of
the drive in a closed-loop pressure and position control. Reference and disturbance
responses determine the precision of the drive which influences product quality and motion
accuracy in stationary and mobile applications.
This thesis shows by means of linearised mathematical models that the drive performance
can be significantly improved by high dynamics of the control valve. The increase in valve
dynamics can be achieved by the use of piezoelectric actuators, which outmatch the
response of common electromechanical valve actuators.
Within the scope of this work two different novel high-response piezo-servovalves are
prototyped. These are four-way directional flow control valves with linear spools. The
book presents different steps of the design and development process of the valves such as
conceptual design, calculation, dimensioning, manufacturing, design of internal valve
control, testing according to the internationally standardized procedures and comparison to
the performance of common servovalves. The achieved dynamics of the piezo-servovalves
surpasses the response of the conventional valves. Exemplary investigations of an
electrohydraulic cylinder drive show an improved reference response of pressure control
by 50% and an enhanced disturbance response of position control by 40% due to the use of
the piezo-servovalve at the drive.
This work demonstrates that the commercially available piezo-actuators can be successfully
implemented in industrial hydraulic valves, bringing advantages for the overall drive
performance. The high reliability and endurance of the piezo-actuators have already been
proven by the use in common rail fuel injectors in the automobile industry since 2002. Taking
into account falling costs of the actuators due to the mass production for the automobile
industry they can become a very attractive alternative or supplement for hydraulic valve
technology. Kurzfassung
Die Arbeit befasst sich mit der Entwicklung und Erprobung hochdynamischer Piezo-
Servoventile zur Leistungssteigerung elektrohydraulischer Zylinderantriebe. Die
Leistungssteigerung bedeutet im Kontext der Arbeit eine Verbesserung von Führungs- und
Störverhalten des Zylinderantriebs in der Druck- und Lageregelung. Das Führungs- und
Störverhalten eines Antriebs bestimmen seine Präzision, welche für die Qualität der
Erzeugnisse bzw. Genauigkeit der auszuführenden Bewegung entscheidend ist.
Anhand linearisierter mathematischer Modelle wird gezeigt, dass das Antriebsverhalten
vorwiegend durch hohe Ventildynamik verbessert werden kann. Zur Steigerung der
Ventildynamik wird piezoelektrischer Aktor herangezogen, dessen Zeitverhalten das
Verhalten von konventionellen elektromechanischen Ventilaktoren deutlich übertrifft.
Im Rahmen der Arbeit werden zwei Prototypen neuartiger hochdynamischer Piezo-
Servoventile entwickelt. Es handelt sich hierbei um 4/3-Wegeventile in
Längsschieberausführung. Beide Entwicklungen umfassen Konzeptionierung, Berechnung,
Dimensionierung, Konstruktion, Fertigung, Entwurf und Umsetzung ventilinterner
Lageregelung, Erprobung im Versuch nach standardisierten Verfahren und
Gegenüberstellung zu konventionellen Ventilen vergleichbarer Nenngröße. Die erzielte
Ventildynamik übertrifft deutlich die Dynamik konventioneller Servoventile. Beispielhafte
Untersuchungen an einem elektrohydraulischen Zylinderantrieb zeigen, dass durch den
Einsatz der Piezo-Servoventile das Führungsverhalten der Druckregelung bzw. das
Störverhalten der Lageregelung des Antriebs um ca. 50% bzw. 40% verbessert werden
können.
Die Arbeit zeigt, dass kommerziell verfügbare Piezo-Aktoren erfolgreich in den
hydraulischen Industrieventilen zur Leistungssteigerung des Antriebs eingesetzt werden
können. Die hohe Zuverlässigkeit und Lebensdauer dieser Aktoren wurde durch den
Einsatz in Common-Rail-Einspritzsystemen in der Automobilindustrie seit 2002 bereits
nachgewiesen. Durch die geringen Herstellungskosten der Massenfertigung stellen die Kfz-
Piezo-Aktoren eine attraktive Alternative für die industrielle hydraulische
Servoventiltechnk dar. Contents i
Contents
Nomenclature .......................................................................................................................... iii
Abbreviations .......................................................................................................................... ix
Glossary ............................................................................................................................... x
1 Introduction and objectives ........................................................................... 1
2 State of the art ................................................................................................ 4
2.1 Valve controlled electrohydraulic cylinder drives ................................................... 4
2.2 Influence of valve characteristics on drive performance ....................................... 14
2.2.1 Pressure control .................................................................................................... 14
2.2.2 Position control 20
2.3 Previous approaches to increase valve dynamics .................................................. 28
3 Development of directly operated piezo-servovalve ................................... 36
3.1 Valve concept ....................................................................................................... 36
3.2 Valve design ......................................................................................................... 38
3.3 Valve control ........................................................................................................ 51
3.4 Valve performance ............................................................................................... 53
3.4.1 Static performance................................................................................................ 54
3.4.2 Dynamic performance .......................................................................................... 56
3.5 Evaluation of directly operated piezo-servovalve ................................................. 58
4 Development of pilot operated piezo-servovalve ........................................ 60
4.1 Valve concept 60
4.2 Valve design 64
4.2.1 Definition of optimum design parameters ............................................................. 66
4.2.2 Pilot valve design ................................................................................................. 72
4.2.3 Pilot stage design .................................................................................................. 85
4.2.4 Complete valve design ......................................................................................... 88
4.3 Valve control ........................................................................................................ 89
4.4 Valve performance ............................................................................................... 92
4.4.1 Static performance................................................................................................ 92
4.4.2 Dynamic performance .......................................................................................... 95
4.5 Evaluation of pilot operated piezo-servovalve ...................................................... 99
5 Investigation of cylinder drive performance ............................................ 102
5.1 Development of test-rig ...................................................................................... 102
5.2 Pressure control .................................................................................................. 104
5.2.1 Control structure ................................................................................................. 104
5.2.2 Testing ............................................................................................................... 109
5.3 Position control 112
5.3.1 Control structure 112
5.3.2 Testing117
ii Contents
5.3.3 Simulation .......................................................................................................... 121
6 Summary and outlook ................................................................................ 129
7 Bibliography ............................................................................................... 131
Nomenclature iii
Nomenclature
2A spool frontal area [ m ]
2A area of contact surface C [ m ]
2A piston area of cylinder drive cd [ m ]
2A passage area at valve inlet in [ m ]
2A passage area at valve outlet out [ m ]
2A passage area of pilot valve P [ m ]
3 2B orifice flow coefficient [ (m /s)/(m N/m ) ]
C electrical capacitance of piezo-actuator el. [ F ]
3 2C hydraulic capacitance h [ m /(N/m ) ]
3 2C hydraulic capacitance of chamber A h,PA [ m /(N/m ) ]
3 2C hydraulic capacitance of chamber B h,PB [ m /(N/m ) ]
C velocity gain of cylinder drive 0 [ 1/s ]
c stiffness of piezo-actuator piezo [ N/m ]
c stiffness of plate spring spring [ N/m ]
c stiffness of total dynamic system total [ N/m ]
D damping ratio of cylinder cd [ - ]
D damping ratio of piezo-actuator attached to sleeve [ - ] sleeve
D damping ratio of linear force motor attached to spool [ - ] spool
D damping ratio of total dynamic system total [ - ]
D damping ratio of valve v [ - ]
Dm plug diameter of pilot valve P [ m ]
Dm diameter of spool frontal area spool [ m ]
d damping coefficient of piezo-actuator piezo [ Ns/m ]
d damping coefficient of plate spring spring [ Ns/m ]
d damping coefficient of total dynamic system total [ Ns/m ]
d damping coefficient of cylinder drive [ Ns/m ] x
2E´ bulk modulus of oil and tubes [ N/m ]
F force of valve actuator act. [ N ]

Un pour Un
Permettre à tous d'accéder à la lecture
Pour chaque accès à la bibliothèque, YouScribe donne un accès à une personne dans le besoin