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This paper studies the proportional directional control valves design influence on the energetic behavior of a mid-power compact excavator. In particular, with reference to the hydraulic circuit actuating the primary workgroup, in the paper the hydraulic power metering performed with the boom cylinder proportional control valve is studied, and some design solution useful in reducing both the hydraulic power dissipation, and the power absorption from the machinery prime mover are highlighted. The analysis, experimentally performed for different operating conditions, is carried out highlighting the influence of a metering configuration both on the supply pressure modulation and on the flow-rate supplied to the actuator.

This paper studies the influence of the discharge chamber geometrical parameters on the steady-state characteristics behavior of a conical seat valve having compensating profile. More in details, starting from the analysis of the experimental behavior of an actual valve showing inefficient characteristic curves, the metering openings leading to the transition from under to over compensation are individuated. Then, a 3D CFD steady-state, incompressible and isothermal analysis is involved, mainly to evidence the valve discharge coefficient and flow-forces variations with operating conditions. After, two alternative valve configurations, presenting a low pressure region designed to optimize the flow-forces compensation, are characterized through the 3D CFD analysis.

The paper investigates, by means of a 3D, steady-state, incompressible and isothermal CFD analysis, the influence of the notch shape and number on proportional directional control valves metering edge characteristics. The numerical activity is firstly performed for a sharp metering edge, considered as reference case. Then, different configurations of notched metering edges are considered, coming from the adoption of two notch geometrical shapes largely used in proportional directional control valves actual design, and from a symmetrical displacement of two, three and four notches on the spool periphery. For all the cases considered, the qualitative analysis of the internal flow field is performed in order to highlight the fluid efflux main characteristics.