A Lumped Parameter Model for the Pressure and Vibration Analysis of Variable Displacement Vane Pumps

This PhD thesis presents a lumped parameter model able to simulate the vibrational behavior of a wide range of variable displacement vane pumps. The vibration analysis of the rotating parts is carried out through a planar model with three degrees of freedom. It takes into account the variability of the pressure loads acting on the rotor shaft, the hydrodynamic journal bearing reactions, the friction due to viscous actions and contact forces, the rotor shaft stiffness and damping, the variation of the pump geometry with respect to working condition and all the inertia actions. In particular, the computation of pressure forces and torques is allowed by the preliminary evaluation of the variable pressure field acting inside the pump, obtained through a model based on an Euler’s approach with 26 control volumes. Thus, the present model makes it possible to define the pressure field acting inside the pump, and calculate the rotor shaft accelerations, as well as the journal bearing reaction forces and the motor drive torque absorbed by the pump in working condition. The test campaign and the validation method are then described: an original assessment technique based on the comparison of pump casing accelerations is proposed. Finally, some important simulation results are reported as an example of application. The main original contribution of this work concerns the development of a nonlinear model of variable displacement vane pumps including all the important dynamic effects in the same model, with the aim at taking into account their iterations. This can be important in order to foresee the influence of working conditions and design modifications on the pump vibrational behavior. In this sense the developed lumped parameter model could be a very useful tool in prototype design, in order to identify the origin of unwanted dynamic effects.