Dynamic modeling and vibration response analysis of an internal gear pump

The dynamic behavior of internal gear pump is complex, and the dynamic model is of significance for capturing its dynamic vibration responses. This study builds a dynamic model consisting of four masses with 20 degrees of freedom. The main components of the internal gear pump are simplified using multiple lumped mass points connected to each other by spring-damping elements. The dynamic excitation forces are computed by utilizing the chamber pressures simulated with a lumped parameter (LP) model. The construction of an experiment apparatus is undertaken to validate the accuracy of LP model and dynamic model. The experiment results show the effectiveness of both models. Employing the developed model, the study investigates the influences of the outlet pressure and rotary speed on the vibration responses and phase trajectory. The results reveal that the fundamental frequency of the pump and its orders are determined by the rotary speed, and the order vibration responses escalate with an increase in outlet pressure. The phase trajectory figures undergo distinct changes at various working conditions. As the rotary speed increases, the irregular movements might be varied into less irregular movements. These results show the vibration response characteristics of internal gear pump at various working conditions.