Hydraulic Hybrid Excavator—Mathematical Model Validation and Energy Analysis

Abstract

Recent demands to reduce pollutant emissions and improve energy efficiency have driven the implementation of hybrid solutions in mobile machinery. This paper presents the results of a numerical and experimental analysis conducted on a hydraulic hybrid excavator (HHE). The machinery under study is a middle size excavator, whose standard version was modified with the introduction of an energy recovery system (ERS). The proposed ERS layout was designed to recover the potential energy of the boom, using a hydraulic accumulator as a storage device. The recovered energy is utilized through the pilot pump of the machinery which operates as a motor, thus reducing the torque required from the internal combustion engine (ICE). The analysis reported in this paper validates the HHE model by comparing numerical and experimental data in terms of hydraulic and mechanical variables and fuel consumption. The mathematical model shows its capability to reproduce the realistic operating conditions of the realized prototype, tested on the field. A detailed energy analysis comparison between the standard and the hybrid excavator models was carried out to evaluate the energy flows along the system, showing advantages, weaknesses and possibilities to further improve the machinery efficiency. Finally, the fuel consumption estimated by the model and that measured during the experiments are presented to highlight the fuel saving percentages. The HHE model is an important starting point for the development of other energy saving solutions.

Experimental Study on the Influence of the Rotating Cylinder Block and Pistons on Churning Losses in Axial Piston Pumps

“…Axial piston pumps are widely used in fluid power systems for advantages such as high power-mass ratio, high limit load pressure and high overall efficiency [1][2][3]. Figure 1 illustrates the general configuration of a conventional axial piston pump consisting of several pistons mounted within the cylinder bores at equal angular intervals around the centerline of the cylinder block.…”

Effect of Zonal Hydraulics on Energy Consumption and Boom Structure of a Micro-Excavator

“…An excavator is an example of construction machinery with its own challenges, such as various working cycles, a variety of end tools, and the size of the machine in general. Academic studies related to excavators mostly concentrate on electrification and hybridization on swing and boom motion to recover the kinetic and potential energy [3][4][5]. For instance, [6] proposed a hybrid drive in a 20-tonne excavator.…”

Energy Efficiency and Controllability of Fluid Power Systems

“…Casoli et al [4] presents a study on a hydraulic hybrid solution for mobile machines that allows for energy recovery during the assistive phases of the linear actuators. The proposed solution is easy to implement and it can retrofit an existing load sensing system.…”

“…These gaps play a key role in determining the energy efficiency of the pump as well as its durability. While traditional study approaches for these lubricating interfaces assume full film lubrication, in [4] a numerical method that include the presence of mixed lubrication effects is investigated. The simulation results and an experimental activity on a commercial unit show how mixed lubrication effects allow for a better understanding of the pump lubricating mechanism also in normal operating ranges.…”

“…New approaches for the analysis, modeling, and design of hydraulic and pneumatic components This book contains the successful invited submissions [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] to the Special Issue.…”