Modelling of a Variable Displacement Lubricating Pump with Air Dissolution Dynamics
Abstract The simulation of lubricating pumps for internal combustion engines has always represented a challenge due to the high aeration level of the working fluid. In fact, the delivery pressure ripple is highly influenced by the effective fluid bulk modulus, which is significantly reduced by the presence of separated air. This paper presents a detailed lumped parameter model of a variable displacement vane pump with a two-level pressure setting, in which the fluid model takes into account the dynamics of release and dissolution of the air in the oil. The pump was modelled in the LMS Imagine.Lab Amesim® environment through customized libraries for the evaluation of the main geometric features. The model was validated experimentally in terms of pressure oscillations in conditions of low and high aeration. The fraction of separated air in the reservoir of the test rig was measured by means of an X-ray technique.