Abstract
Pressure and flow ripples of a variable-displacement vane-pump with a pressure compensator were analyzed by numerical calculations, and their results were compared with experiments. The behavior of the leakages and the other factors affecting pressure ripples were examined in detail. It was proved that the apparent leakages due to a fluid compressibility in both compression and expansion processes of a confined pumping chamber influence definitely the ripples of pressure and flow, and that a transient pressure curve of the chamber and its bulk modulus are important. Furthermore, it was shown that the pressure ripples in the regulating region (the pressure-compensated state) become extremely larger than those in the non-regulating region according to the vibration of a cam-ring excited by the fluctuating internal force induced by a variation of the numbers of chamber exposed to the delivery port.
