The Effects of the Design Parameters on the Generated Curvature and Displacement of Epitrochoidal Gerotor Pumps

The wear characteristics and, therefore, the failure rate of a gerotor are highly dependent upon the minimum radius of curvature of the generated shape of the working chambers. The paper shows that the minimum radius of curvature may be increased without increasing the overall size of the gerotor or substantially decreasing the pocket displacement. The design parameters that affect the radius of curvature are: the radii of the fixed and moving pitch circles, the radius of the generating pin, the distance from the center of the pitch circle containing the generating pin to the center of the generatng pin, and the ratio of the pitch circles. The paper includes an equation for the pocket displacement as a function of these design parameters and the input angle. The paper also presents important relations between the curvature of the generated shape, the displacement, and the package size.