Computerized generation and stress analysis of internal bevel gear drives with modified spherical involute tooth profiles

Internal straight bevel gear drives are primarily used in pericyclic transmissions, which are suitable for electric vehicles and aircraft flight control systems due to their high gear ratios. Unlike external straight bevel gears, internal straight bevel gears have not been extensively studied. In this paper, the computerized design of internal straight bevel gear drives is presented. The tooth surfaces are generated using a theoretical approach where a crown gear with spherical involute profile is applied. The theoretical surfaces are then modified considering micro-geometry deviations, requiring the use of Hermite curves to conform the fillet surfaces. Additionally, a method for detecting secondary interference during meshing, based on tooth contact analysis, is introduced. Although this type of gear drive exhibits a conformal contact due to the convex-concave shape of the mating tooth surfaces and a high contact ratio could be reached, stress analysis indicates that the power transmission is limited by their bending behavior. A numerical example is provided to illustrate the developed theory.