Innovative and self-adaptive energy recovery system in hydraulic cylinders for cyclic operations

• Published in: Journal of physics. Conference series 2024-11, Vol.2893 (1), p.012059
• Main Authors: Romagnuolo, Luca, Frosina, Emma, Hieronymis, Carlo Rozzi de, Bordini, Giorgio, Senatore, Adolfo
• Format: Article
• Language: English
• Subjects: Accumulators; Actuation; Actuators; Adaptive control; Adaptive systems; Chambers; Cyclic loads; Earthmoving equipment; Energy; Energy dissipation; Energy recovery systems; Excavators; Feedback control; Gas pressure; Hydraulic equipment; Hydraulics; Manifolds; Phase (cyclic); Pressure loss; Rare gases; Recovery; Thermal cycling
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/2893/1/012059

Conventional hydraulic actuation supply and control systems usually work with a very high energy loss, especially in the field of off-road machinery. In particular, during the lowering phase of a boom of a hydraulic excavator, energy dissipated through lamination in thermal heat is a consistent fraction of the energy required for operating the working cycle. In this paper, an innovative system is presented that can recover a significant fraction of this energy, to make it available for the next working cycle, which adapts the level of energy recovery in order to maximise the overall efficiency.In the presented system, the conventional hydraulic actuators that operate the boom of a large size hydraulic excavator are replaced with three-chamber actuators, in which the third chamber, obtained inside the cylinder rod, is connected to a secondary hydraulic circuit that involves a series of accumulators: the compression and the subsequent expansion of the amount of gas inside the accumulator allows to, respectively, store the maximum possible recoverable energy, during load lowering phase in the first cycle and deploy it in the next cycle. The initial gas pressure inside the accumulator is set accordingly to the maximum amount of recoverable energy during the cyclic operation, and can be easily changed via a low-displacement auxiliary pump and a feedback control mechanism, without the need of stopping the machine to vary the amount of inert gas inside the accumulators.A hydraulic manifold has been designed to manage and regulate the flow rates of both the main and the secondary circuits. Pressure losses inside the manifold have been evaluated through CFD analysis, performed in SimericsMP+ environment. The whole system has then been simulated as a lumped parameter model developed in Simcenter Amesim ©. Results from the simulation of the proposed system show that, on a working cycle of 20 s, only 25% of the hydraulic energy required for the conventional system is needed to operate the boom in the proposed configuration.This method can be easily extended to several hydraulic actuators that realise frequent height changes of the load.