ABSTRACT
Mobile machines with hydraulic drives, which are designed to perform loading and unloading operations, are widely used in industry and require precise displacement of work units, as well as the ability to maintain them for a certain period of time. The scheme of a proportional electrohydraulic directional control valve with independent flows control which provides proportional control of flows at the inlet and outlet of the hydraulic unit, and also the possibility of its fixation, is presented. To improve the controllability of the proportional electrohydraulic directional control valve, it is proposed to apply feedback elements. The results of research, which are based on a developed mathematical model, show a positive effect from using feedback elements and improve the proportionality of the control. Investigations of the influence of the design parameters of the proportional electrohydraulic directional control valve on overshoot of the pressure in the hydraulic drive have been carried out. Using feedback does not lead to a significant deterioration of the dynamic characteristics of the hydraulic drive, but it is important that a rational combination of design parameters must be chosen.
