A Study on Structureborne Noise of Hydraulic Gear Pumps

The main source of vibration and noise in hydraulic systems is the flow ripple at the pump output which interacts with the downstream components and generates pressure ripple in the current, structureborne noise in mechanical parts and airborne noise in the environment. The present research was suggested by the observation that some peaks in the airborne noise spectrum of a specific pump family were within a frequency range far from those typically related with the fluidborne or structureborne noise; unfortunately, in that range the human ear does not filter the noise efficiently. In general, the investigation of the interaction between fluidborne noise and structurebornenoise can be carried through both "macro-analysis" techniques (sound emission analysis, pressure ripple measurement, modal analysis, etc.) and "micro-analysis" techniques (contact mechanics of gears, performance of the bearing system, etc.). The present research started from a "macro" approach inclusive of the modal analysis of a gear pump, the measurement of its pressure ripple and its acoustic mapping though the sound intensity technique. Currently, the focus is on the "micro" approach and specially on the investigation of the elasto-hydrodynamic bearing performance in view of deriving the influence of the bearing geometry on the overall structureborne noise.