Gears having a tooth-profile with a smaller relative of curvature at a contact point

Abstract

The gears according to the present invention have a unique tooth-profile in which the radius of curvature repeatedly increases and decreases from the pitch line in the direction of addendum and deddendum of a tooth without monotonously changing, and at the point where the relative of curvature is minimum, the center of the radius of curvature is positioned on the pitch line. Specifically, the curvature of the tooth-profile curve is a function which is not monotonously varied, is continuous and is capable of being differentiated, and a locus of the center of curvature forms a series of continuous curves which exist near the pitch circle. Forming the tooth-profile thus enables the relative of curvature to be brought from the value in the involute gear near that of a Wildhaver-Novikov type, with the contact interval being more than one. Also, the operating pressure angle is decreased to prevent the increase in the surface pressure and the bearing stress, and the relative of curvature between the tooth-surfaces of the gears is maintained at a lower level than the conventional one, markedly increasing the strength of the tooth-profile. The present invention can also be applied to internal gears, bevel gear, etc.

Dependencies are inferred from the claim text.