Patent ID: 9052010
Filing Date: 2015-06-09
Classification: F16H,Y10T

Abstract:
1. A gear having an involute tooth surface, wherein: a tooth right-angled cross-sectional shape in a tooth bottom side area of a tooth has line symmetry with respect to a line connecting a tooth bottom center and a gear center; a half of the tooth right-angled cross-sectional shape in the tooth bottom side area of the tooth divided at the tooth bottom center as a boundary is defined by the first involute portion is formed so as to be increased in radius of curvature with distance from the tooth bottom center; the arcuate portion is formed into an arcuate shape so as to have the same radius of curvature as the maximum radius of curvature of the first involute portion; the second involute portion is formed such that the radius of curvature of the second involute portion at a connecting portion to the arcuate portion is the same as the radius of curvature of the arcuate portion, and such that the radius of curvature of the second involute portion increases with distance from the arcuate portion; the third involute portion is formed such that the radius of curvature of the third involute portion at a connecting portion to the second involute portion is the same as the maximum radius of curvature of the second involute portion, and such that the radius of curvature of the third involute portion decreases with distance from the second involute portion; the tooth surface connecting curved portion is formed of a smooth curved line which does not cause a stress concentration in a connecting area between the third involute portion and the tooth surface; the connecting portion between the second involute portion and the third involute portion is set to be positioned at a dangerous section position in a Hofer's 30 degrees tangent method; and the radii of curvature of the first involute portion, the arcuate portion, the second involute portion and the third involute portion are determined so that a stress variation width in a stress state of a partly reverse state caused by a tensile stress and a compression stress generated in the tooth bottom side area of the tooth before and after the meshing of the tooth is uniformized.