Design and Performance of small tooth number gear with non-conventional tooth profile

Abstract

Involute curves are mainly used for gears. However, involute gears likely occur tooth undercutting, pointed tooth, and reduction in contact ratio as number of tooth decrease. On the other hand, cycloid gears, similarly involute gears, can transmit motion at a constant speed ratio. Although cycloid gears are not suitable for power transmission because of significant increase in contact stress at the pitch point. In this study, we designed an inconvertibility cycloid gear, an involute- cycloid composite gear, a modified cycloid gear and an asymmetric involute gear, which gears have small tooth number. Inconvertibility cycloid gears prevent contact at the pitch point by using epi-cycloid tooth profile for the pinion and hypo-cycloid one for the wheel. Involute-cycloid composite gears use an involute curve near the pitch point. Modified cycloid gears remove the curve near the pitch point attempt to reduce contact stress. Asymmetric involute gears have different pressure angles between the working flank and the non- working one to prevent tooth undercutting at the tooth root and pointed tooth at the tooth tip. Driving tests were accomplished using these gears with the power absorption gear testing machine, and discussed the driving performance.