Assessment of contact forces and stresses, torque ripple and efficiency of a cycloidal gear drive and its involute kinematical equivalent

In this paper, we assess and compare a conventional cycloidal drive and its involute-tooth kinematical equivalent via finite element (FE) and dynamical multi-body analysis. The analysis of the stiffer conventional cycloidal configuration reveals multiple points of contacts, although some of these have little contribution to the torque transmission. Significant non-torque loads are self-induced, with contact forces constantly changing in magnitude and orientation, consistently with the contact characteristics of the cycloid. In the involute alternative, the stress concentration was more localized to two or three points of contact, according to the involute contact ratio, leading to increased stresses. The contact forces remained constant relative to the tangential direction, as per the constant involute pressure angle, contributing to desirable torque loads. The torque ripple was found to have two components, one at the tooth engagement frequency (fz) and one at the high-speed shaft rotation frequency (fn), the former being more pronounced in the conventional cycloidal case, while the latter being larger for the cycloidal drive with involute teeth. Moreover, both analytical calculations and the multi-body dynamics simulations suggest that the involute-tooth design is more efficient compared to the conventional cycloidal-tooth design.