Reduction of friction torque in vane pump by smoothing cam ring surface

Abstract

This work deals with the influence of surface roughness of cam contours on friction torque in a hydraulic balanced vane pump and it is verified that smoothing the surface of the cam contour can reduce friction torque. In the vane pump, the friction torque arising from the friction between a cam contour and vane tips is significant. In this article, first, the values of the coefficient of friction between the vane tip and its sliding surfaces were measured by using cylindrical test rings with various kinds of surface roughness. Then the torque characteristics of vane pumps having cam ring contours with various values of surface roughness were measured and their results compared with the results of an analysis of the coefficient of friction investigated using test rings. As a result, the friction torque caused by the friction between the cam contour and the vane tip was reduced by lessening the surface roughness of the cam contour, resulting in an improvement of the mechanical efficiency. The coefficient of friction measured by using the test rings could be applied to the actual vane pumps.