Development of an unconventional electro-hydraulic proportional valve with fuzzy-logic controller for hydraulic presses

In this study, an unconventional electro-hydraulic proportional flow control valve based on a switching solenoid and a fuzzy-logic controller is proposed for application to hydraulic presses. The main purpose of this study is the attempt to develop an electro-hydraulic proportional flow control valve with lowest cost. Since the switching solenoid possesses quite nonlinear force/stroke characteristics, it is basically not suitable for the development of hydraulic proportional valves. Therefore, the fuzzy-logic controller is employed to linearize the force/stroke characteristics. The basic idea is the utilization of the numerically estimated pseudo-force as the feedback signal. Finally, this newly developed electro-hydraulic proportional flow control valve is installed in a hydraulic press. Experimental results show that the control of the ram velocity of the press cylinder using the proposed electro-hydraulic proportional flow control valve is quite successful.