A throttle-less single-rod hydraulic cylinder positioning system: Design and experimental evaluation

Abstract

Modern industrial tote dumpers and lifters are equipped with long-stroke single-rod hydraulic cylinders. For years, valve-controlled cylinders have been used in tote dumpers. Valve-controlled actuators are highly inefficient due to huge power losses in throttling valves. They also need a cooling system to remove the wasted heat energy from the hydraulic oil. This article introduces a low-cost throttle-less hydraulic circuit to control the single-rod cylinder of a tote dumper. The system consists of a motor-driven gear pump, an On/Off solenoid valve, to redirect the differential flow of the single-rod hydraulic cylinder and a counterbalance valve, which makes the circuit controllable for assisting loads and keeps the load in position with no effort from the hydraulic pump. Experimental results demonstrate the performance of the circuit. A test rig has been designed to simulate a lifting load. The energy efficiency of the circuit is determined by comparing a valve-controlled circuit with the proposed circuit. The proposed circuit composition is not only efficient and simple but is also accurate in terms of position response using a proportional controller. The circuit is easy to control since the only needed measurement is the displacement of the actuator. The circuit, however, does not recycle energy.