الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 114 |  |  |
| | | from | 114 | | |
Abstract
The increase in automation makes it ever more necessary for pressure, flow rate and flow direction in hydraulic systems to be controlled by means of an electrical control system. The obvious choices for this are proportional and servo valves as an interface between controller and hydraulic system. These valves are continuous acting valves which are the final control elements in open and closed control loops to precisely control the position, velocity or force of an actuator of a hydraulic system. The static and dynamic characteristics of the valves affect the overall characteristics of the hydraulic circuit.
It was known that the servo valve cost for specific application is about 6 times that of the proportional valve. So, for reasons of cost the present study aimed at if one can fix a proportional valve in place of a servo valve in servo hydraulic systems. Also, important is whether or not the new dynamic performance would be in the accepted zone.
A hydraulic testing system was made available and experiments conducted to study the dynamic performance changes due to valves exchange. Results indicated that the response deviation in servo valve was very low compared to that of proportional valve and the
transient response time was low in the servo hydraulic valve compared to proportional valve.
For reasons of cost and sometimes unavailability of servo valves, proportional directional control valves may be applied in closed control loops ifthe reduction in dynamic performance requirements is accepted.