Rotating group design for vane pump flow ripple reduction

Abstract

It is well known that the hydraulic pump is the main source of noise in hydraulic power steering systems. This noise is produced by the pulsating flow transmitted through the fluid due to the cyclic pumping mechanism. This flow ripple and pressure ripple spread through the hydraulic circuit, interacting in a complex way with other parts of the vehicle. This process generates annoying audible noise inside the vehicle. This work addresses a new approach to flow ripple reduction by tuning the pump rotating group. The method consists of making the outlet flow as steady as possible by modifying the rotating group geometry. A MATLAB/Simulink-based pump model has been created according to the new geometrical characteristics and their numerical results, compared to the regular pump ones. In addition, a flow ripple experiment was conducted using the secondary source method (SSM to validate the numerically-predicted results of the regular pump. The results of the new design show significant amplitude reduction of the flow ripple amplitudes at different operating conditions. In particular, the flow ripple reduction at the first harmonic is almost 20 dB when the pump runs in a parking manoeuvres operating condition (1000 rpm at 50 bar of backpressure).