Electrohydraulic servovalves – past, present, and future

• Main Author: Plummer, Andrew
• Other Authors: Dresdner Verein zur Förderung der Fluidtechnik e. V. ,
• Format: Others
• Language: English
• Published: Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden 2016
• Subjects: Servovalve; Direct drive valve; Nozzle-flapper; Piezoelectric; ddc:620; rvk:ZQ 5460
• Online Access: http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-200252; http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-200252; http://www.qucosa.de/fileadmin/data/qucosa/documents/20025/7-0_PDF_A_General%20Lecture%20Electrohydraulic%20servovalves%20%E2%80%93%20past%2C%20present%2C%20and%20future.pdf

In 2016 it is 70 years since the first patent for a two-stage servovalve was filed, and 60 years since the double nozzle-flapper two-stage valve patent was granted. This paper reviews the many alternative servovalve designs that were investigated at that time, focusing on two-stage valves. The development of single-stage valves – otherwise known as direct drive or proportional valves – for industrial rather than aerospace application is also briefly reviewed. Ongoing research into alternative valve technology is then discussed, particularly focussing on piezoelectric actuation and the opportunities afforded by additive manufacturing.