Energy Consumption in ICE Lubricating Gear Pumps

Scope of this work is the analysis of the energy consumed by lubricating gear pumps for automotive applications during a driving cycle. This paper presents the lumped parameter simulation model of gerotor lubricating pumps and the comparison between numerical outcomes and experimental results. The model evaluates the power required to drive the pump and the cumulative energy consumed in the driving cycle. The influence of temperature variations on leakage flows, viscous friction torque and lubricating circuit permeability is taken into account. The simulation model has been validated by means of a test rig for hydraulic pumps able to reproduce the typical speed, temperature and load profiles during a NEDC driving cycle. Experimental tests, performed on a crankshaft mounted pump for diesel engines, have confirmed a good matching with the simulation model predictions in terms of instantaneous quantities and overall energy consumption. The study allowed a proper screening of the power waste due to the pressure relief valve, the friction torque and the leakage losses during different stages of the engine warm-up. The outcomes from the simulation have brought to evidence that the main contribution to the consumed energy is due to the viscous friction torque, above all during the first urban cycle. Moreover, the influence of some parameters, such as the pressure setting of the relief valve and the temperature rate has been analyzed. Finally the model has been applied to an off-axis mounted gerotor pump with smaller gears diameters to quantify the improvement in power saving due to the reduction of viscous friction.