Numerical Analysis on the Effect of Dissolved Air on the Pressure Chamber Dynamics of a Variable Displacement Oil Pump

Variable-displacement lubricating pumps are an attractive solution for reducing fuel consumption and emissions in motorcycle engines. In this prospective, modelling and experimental analysis are very useful means for a deeper understanding of pump operation and for effectively implementing pump control. Zero-dimensional simulation results of a 7-vane pump were compared with the experimental data of dynamic piezoresistive pressure transducers fitted into the casing of a pump prototype, which was operated under steady-state conditions at different rotational speeds and eccentricity values. The experimental data exhibit oscillations which were explained by taking into account the pressure transducers dynamics, as a result of the transducer location in the pump casing, of the air dissolved in the hydraulic fluid and of the geometry of the tubing/transducer system. The investigation shows that the transducer dynamics deteriorate as the diameter or length of the connections increase and as the dissolved air quantity increases.