Tribo-dynamics of balanced vane pumps for automotive applications and experimental validation

Balanced vane pumps may encounter both loss of contact and elasto-hydrodynamic lubrication (EHL) conditions at the vane tip, affecting Noise-Vibration-Harshness (NVH) and durability. This paper introduces a tribo-dynamic model of the balanced vane pump to estimate the Oil Film Thickness (OFT) at the vane tip, facilitating the assessment of these phenomena. A single-degree-of-freedom lumped parameter model describes the radial displacement of the vane, considering the loss of contact, parametric excitation due to time-varying contact stiffness, and the pressure force acting within the under-vane pocket and displacement chambers. The lubrication model addressing both EHL and hydrodynamic lubrication (HL) conditions is presented. The EHL model, based on a finite difference scheme, determines the contact pressure distribution and OFT shape in the lubricated junction, whereas the HL model is based on an analytical solution. Experimental validation confirms the model reliability, supporting its use in improving vane pump design.