Abstract
Counterbalance Valves (CBVs) are commonly adopted in load handling machines such as cranes, winches, and telehandlers. Besides their load-holding and relief functionality, they allow establishing a counterpressure so that simple meter-in control approaches can properly operate in case of overrunning loads. However, the CBV operation often implies excessive energy consumption due to an over-pressurization of the hydraulic system. Past work performed by the authors’ team addressed a solution for using CBVs with controllable pilot, which permits to achieve up to 90% energy saving during overrunning load conditions, when compared to the traditional configuration of CBVs. This past effort focused on steady-state operation, and did not provide a proof that such high energy efficiency solution can operate in dynamic conditions typical of many load handling machines. To address this aspect, this paper built on the mentioned past work and proposes a control strategy that minimizes the energy consumption of the system while meeting the dynamic requirements of a reference application, a truck mounted hydraulic crane. The proposed controller was designed by using a numerical model of the reference machine; afterwards it was tested on real experiments. The results allowed confirming the previous prediction of up to 90% improvement in efficiency, while meeting or exceeding the dynamic performance, as quantified by the measurements of the acceleration signal of the crane arms.
