Spannungswellengetriebe mit einem kurzen, flexiblen Becher-Element

摘要

A cup-type harmonic gear drive (1) comprises a rigid circular spline (2), a cup-shaped flexspline (3) disposed inside the circular spline(2) and a wave generator means (41,42,43) fitted inside the flexspline for flexing the flexspline (3) into elliptic to engage it with the circular spline (2) and for rotating the engagement portions to thereby produce relative rotation between the splines. The flexspline has a tube (3), a disc-shaped diaphragm (32) connected integrally to the end of said tube to define the cup bottom, and a thick boss (33) formed on the center of the diaphragm. The diaphragm (32) has a root portion from the boss (33), a thickness of which is set at least about three times the minimum thickness of the diaphragm. The outer profile of the diaphragm (32) is defined, when viewed along a plane including the axis of the flexspline, by a plurality of curves having a different curvature. These curves are arranged from one having a larger curvature from the root protion to the tube portion of the diaphragm (32). Thus, the stress distribution of the flexspline (3) can be made smooth to the extent for practical use even where a shorter flexspline is adopted.