A Hybrid LP/FE Model for the Dynamic Analysis of External Gear Pumps

Abstract

In this work a hybrid lumped-parameter finite-element model of an external gear pump for automotive applications is presented and experimentally assessed; the finite element (FE) model regards the external parts of the pump (case and end plates) while the lumped-parameter (LP) model regards the interior parts (bushes and gears). The LP model is a non linear kineto-elastodynamic model and includes the most important phenomena involved in the pump operation as time-varying oil pressure distribution on gears, time-varying meshing stiffness and hydrodynamic journal bearing reactions. A forced vibration analysis has been carried out by means of the FE model for the evaluation of the acceleration levels on the external surfaces of the pump; for this analysis, the damping has been estimated using data coming from an experimental modal analysis (EMA) whereas the excitation forces, acting on the internal surface of the case due to bearing reactions and pressure forces, have been obtained from the LP model. In this sense the model is globally a hybrid LP/FE model. The model has been assessed using experiments: the experimental accelerations measured during run-up tests have been compared with the simulated accelerations coming from the FE/LP model. Finally the assessed model has been used in order to identify the effects of design parameters in terms of case vibrations.