Hybrid method to analysis the dynamic behavior of the ring gear for the internal gear motors and pumps

Prediction of the ring gear trajectory inside its housing is a fundamental issue for analysis of the dynamic behavior of the internal gear motors/pumps. However, it is not easy because of lots of phenomenon happening inside motors/pumps. The mobility method introduced by Booker proves that it can predict well the trajectory of the journal bearing by considering the effect of hydrodynamic lubrication regime of the oil film. Unlike journal bearings, the oil film in the internal gear motors/pumps is the combination of two simultaneous regimes; e.g., hydrodynamic and hydrostatic lubrication. This paper presents a hybrid method by adding the effect of hydrostatic lubrication into the original mobility method. A test rig is then designed and built up to validate the simulation results. The theoretical and experimental results have a reasonable agreement. Comparison the calculation and experimental results points out that the deviation of the eccentricity for mobility method is about 14.5 %. Meanwhile, the deviation for the hybrid method is about 3 %. Meaning that with hybrid mobility method increases the accuracy of calculation of the ring gear orbit.