High-strength gear

Patent metadata

Field	Value
Publication number	US-10584783-B2
Application number	US-201615560461-A
Country	US
Kind code	B2
Filing date	Mar 29, 2016
Priority date	Mar 30, 2015
Publication date	Mar 10, 2020
Grant date	Mar 10, 2020

Abstract

A gear keeping the bending stress at the dedendum from becoming locally high at the time of power transmission and thereby raising the dedendum bending strength. The radius of curvature is maximum at a critical section position determined by the Hofer's 30° tangent method. Both radii of curvature from the critical section position to the first and second connecting points X1 and Y1 are constant or decreasing. In dedendum line segment 23, there are points A1 and B1 where radius of curvature is smaller than the critical section position. In the dedendum line segment 23, the maximum radius of curvature is 3 times or less the minimum radius of curvature. By a cross-sectional view, the critical section position is part of an arc, and the arc extends to the two sides of the critical section position. Thus, the maximum bending stress becomes smaller and dedendum bending strength is improved.

First claim

The invention claimed is:

1. A high strength gear having, in cross-sectional view, a tooth profile of an addendum line segment, a tooth surface line segment, a dedendum line segment, and a tooth root line segment successively connected,
wherein a maximum radius of curvature is at a critical section position, the critical section position being determined by the Hofer's 30° tangent method, the critical section position being a point in the dedendum line segment,
a radius of curvature from said critical section position to a first connecting point of a boundary point of said tooth surface line segment and said dedendum line segment is constant or decreases and a radius of curvature from said critical section position to a second connecting point of a boundary point of said dedendum line segment and said tooth root line segment is constant or decreases,
in said dedendum line segment, there is a point where the radius of curvature is smaller than said critical section position,
in said dedendum line segment, a maximum radius of curvature is 3 times or less a minimum radius of curvature, and
said critical section position is positioned on an arc having a constant radius of curvature and said critical section position is not an endpoint of the arc.

2. The high strength gear according to claim 1 , wherein said arc extends in said addendum line segment direction and said dedendum line segment direction based on said critical section position by a tooth depth direction dimension of 0.05 time or more of a module.

3. The high strength gear according to claim 2 , comprised of a ferrous alloy.

4. The high strength gear according to claim 1 , comprised of a ferrous alloy.

Assignees

• Nippon Steel & Sumitomo Metal Corp
• Nippon Steel Corp

Inventors

• Narumiya Hiroki
• Kada Osamu
• Fujita Takashi
• Neishi Yutaka

Classifications

• F16H55/0806 Primary

  Involute profile · CPC title

• F16H55/06

  Use of materials; Use of treatments of toothed members or worms to affect their intrinsic material properties · CPC title

• F16H55/088 Primary

  with corrections on tip or foot of the teeth, e.g. addendum relief for better approach contact · CPC title

• F16H55/08 Primary

  Profiling · CPC title