Feasible design region and sealing property of hypotrochoidal gerotor geometry

Abstract

This paper proposes a method on how to correctly determine the feasible design region without any undercutting on the outer and inner rotor profiles. The non-undercutting equations are derived by the theory of gearing and the feasible design region is determined by considering the non-undercutting curves of the inner and the outer rotors. Numerical examples show that the non-undercutting curves of the inner rotors are above the non-undercutting curves of the outer rotors. So, there is no undercutting on the outer and inner rotors when the parameter is given under the region of the non-undercutting curve of the outer rotor. Besides, the curvature equations of the outer and inner rotors are derived for assessing the sealing property and forecasting the variation of Hertz stress. The sealing property will be an inferior quality in the larger curvature difference region, and the larger variation of Hertz stress would also be predicted.