Improving resolution of digital hydraulic valve system by utilizing fast switching valves

A Digital flow control unit (DFCU) consists of a certain number of parallel connected on/off-valves, which are basically controlled by using pulse code modulation (PCM). In order to limit costs and installation space the number of valves in a DFCU has to be kept as low as possible. As a consequence the relative control resolution of such a system is limited especially for small flow rate of the DFCU. In the presented paper the use of fast switching valves for improvement of the control resolution of a cylinder drive is studied. Experimental measurements are presented and analyzed.