Design and Analysis of the Dual-rotor Gerotor Pump with “K-floid” Profile

Abstract

Nowadays one trend of automotive transmission system is that gerotor pump is widely applied for power train lubrication due to its compact size and low cost. The most of traditional gerotor pumps are designed with trochoid curve. In order to obtain higher volumetric efficiency of the gerotor pump applied in transmission of All Wheel Drive (AWD) vehicles, a new gear profile so-called K-floid is designed. The K-floid profile of the inner rotor is designed by combination of three segments: hypotrochoidal curve, epitrochoidal curve, and common tangent line. The outer rotor profile coordinate is then obtained by means of rotation of the inner rotor. On the other hand, design of a dual-rotor gerotor pump is also presented in the paper so as to reduce flow rate pulsation. CFD simulation is preformed to validate design effect and results indicate that the designed dual-rotor gerotor pump with K-floid can greatly decrease flow rate pulsation and also improve volumetric efficiency compared with the conventional single rotor pump of trochoidal profile. A prototype pump is also manufactured and tested to prove its performance.