A Study of the Internal Forces in a Variable-Displacement Vane-Pump—Part II: A Parametric Study

Abstract

This is the second part of an analytical study of the internal forces in a variable-displacement vane-pump. It presents a parametric study of the forces and torques applied to the mechanism and the shaft of this pump, as functions of line pressure, the eccentricity, and the design geometry. It is shown that the continuous components of the torque and of the direction of the radial shaft-load vary as a sawtooth wave at twice the vane-frequency while the magnitude of the radial shaft-load varies as a square wave at vane-frequency. The design criterion developed in the first part of this study is used to demonstrate the elimination of the magnitude variations in the radial shaft-load. The intermittent components of the internal forces vary as a pulse train at vane frequency and may produce high-peak pressure pulses which must be closely controlled. The variable-capacity feature of variable-displacement vane-pumps has a significant effect on the torque applied to the mechanism, but only a secondary effect on the overall radial shaft-load.