A COMMERCIAL EXCAVATOR: ANALYSIS, MODELLING AND SIMULATION OF THE HYDRAULIC CIRCUIT

The paper addresses some aspects of an ongoing research on a commercial compact excavator. The interest is focused on the analysis and modelling of the whole hydraulic circuit that, beside a load sensing variable displacement pump, features a stack of nine proportional directional control valves modules of which seven are of the load sensing type. Loads being sensed are the boom swing, boom, stick and bucket, right and left track motors and work tools; instead, the blade and the turret swing users do not contribute to the load sensing signal. Of specific interest are the peculiarities that were observed in the stack. In fact, to develop an accurate AMESim modelling, the stack was dismantled and all modules analysed and represented in a CAD environment as 3D parts. The load sensing flow generation unit was replaced on the vehicle by another one whose analysis and modelling have been developed using available design and experimental data. Although both the Hydraulic Component Design library as well as the Planar Mechanical library were used extensively in the process of modelling the entire circuit, some simplifications became necessary and are detailed in the paper. As the modelling phase was developing, a number of field experiments on the vehicle were also performed: these served the purpose of providing reference data to the end of progressing with the validation phase of the AMESim model. Regarding predictive simulation results, these are appropriately consistent with gathered experimental outcomes. The AMESim model will be instrumental for upcoming analyses that foresee the substitution of the original stack with other load sensing post-compensated modules so to assess with reasonable confidence the effects on potential energy savings.