Abstract

Water hydraulics is both old and new technology area. The first fluid power applications were using water as pressure medium already in 1800-century, but the modern water hydraulics has been rapidly growing just recently in 1980’s and 1990’s. The main reasons for the comeback are environmental and safety aspects. Water hydraulics offers a significant alternative to establish motion control systems in environments, where possible oil leakages can cause serious problems.
 One of the major tasks to solve in modern water hydraulics is to achieve more accurate control systems that todays technology enables. The present water hydraulic control valves are not yet in same technology level than in oil hydraulics. This means that a lot of effort has to be put to develop better and more accurate valve constructions and on the other hand more intelligent control methdos has to be develop to achieve reasonable valve characteristics.
 This paper concentrates to study water hydraulic proportional valves, which are still very new developments in water hydraulics. The steady state and dynamic charateristics of water hydraulic proportional ceramic spool valve is studied both by computer simulation and laboratory tests. Some constructional improvements for the valves are studied and also different control methods are discussed and proposed.

Keywords:  proportional valves, water hydraulics, fluid power