Numerical and experimental analysis of hybrid lubrication regime for internal gear motor and pump

Abstract

This paper addresses the simultaneously existence problem of both hydrodynamic and hydrostatic pressure components in the oil lubrication film in case of internal gear motor and pump. Reynolds equation with concerning hybrid parameter is developed to calculate the hybrid pressure profile. Finite difference method with appropriate boundary condition is then used to solve the Reynolds equation to obtain 2D hybrid pressure distribution. The percentage of hydrodynamic and hydrostatic components corresponding to the change of the working pressure and rotating speed are analyzed. Experimental setup is then designed and built to verify the individual effect of hydrodynamic and hydrostatic action on the performance of the internal gear motor and pump under different working conditions. The numerical and experimental results pointed out that the eccentricity ratio optimal for good hybrid force is from 0.46 to 0.75. The hydrodynamic action increases with the increase of the rotating speed whilst the hydrostatic action increases with the increase of operating pressure. As the rotating speed at maximum value and working pressure at minimum value, the proportion percentage of hydrodynamic component gets the largest value. Whilst the hydrostatic component has the largest proportion percentage at minimum rotating speed and maximum working pressure.