Elliptic gear having a constant velocity portion

摘要

An elliptic gear having a constant velocity portion, wherein a pitch circle is a closed curve composed of: a constant velocity portion pitch curve, in which the radius from the center of rotation is a constant arc; and an inconstant velocity portion pitch curve, which is expressed by a formula of an ellipse in polar coordinates having its pole located at the center of rotation and which merges smoothly into the constant velocity portion pitch curve.