Computer aided design of elliptical gears with circular-arc teeth

摘要

An elliptical gear drive, whose rotation axis coincides with its geometric center, can be used as an oil pump. Rack cutters with circular-arc teeth generate the tooth profiles of circular-arc elliptical gears, which have a convex-concave tooth profile contact. The mathematical model of a circular-arc elliptical gear based on the theory of gearing and gear generation mechanism is also developed. Owing to its complex geometry, the profile of circular-arc elliptical gears may have tooth undercutting and pointed teeth. Design parameters such as pressure angle at pitch point, number of teeth, module, major axis, and circular-arc radius affect the tooth undercutting and pointed teeth of circular-arc elliptical gears. This paper proposes a systematic method to generate the tooth profile of circular-arc elliptical gears without tooth undercutting and pointed teeth. Some numerical examples illustrate the effectiveness of the computerized design process.