Influence of leakage clearance on pressure variation in gerotor pump chambers

Abstract

Gerotors are used as pumps, motors, compressors, etc. and used in a wide range of industrial areas. Gerotors are, as pumps suitable for automotive industry as elements of lubricating systems, steering mechanisms and engines. The main component of gerotor pumps is a pair of toothed rotors. Usually, the outer rotor has a circular profile, while inner one has related coupled trochoid profile. In case of the theoretical ideal profile, contacts are simultaneous at all teeth. However, for a real profile, technological clearance and gaps are unavoidable. The existence of these gaps and clearances causes volumetric losses and consequently, variation of pressure in gerotor pump chambers. For the full understanding of real processes of fluid flow in gerotor pumps, the analytical model of fluid leaking through clearance between the profiles of teeth is presented in this paper. Due to the complexity of the fluid flow process, only volumetric losses caused by gaps between profiles of teeth and losses caused by an act of viscosity forces along the gap are analyzed. The effects of variation of geometrical parameters of profiles on the value of volumetric losses and variation of pressure in chambers of gerotor pumps are analyzed in this paper. Besides, the mutual comparison of pressure variation due to current flow obtained analytically in the pump with a theoretical ideal profile of teeth and with a real profile with gaps and clearances is done. Results and conclusions presented in this paper by highlighting real processes during exploitation bring very important perspectives for gerotor pump design that provides an effective constructional solution.