RING GEAR AND METHOD FOR MANUFACTURING RING GEAR

• US 20190331210A1
• Filed: 09/22/2017
• Published: 10/31/2019
• Est. Priority Date: 09/29/2016
• Status: Active Grant

• Current Assignee: Aisin AW Company Limited (Aisin Corp.)
• Original Assignee: Aisin AW Company Limited (Aisin Corp.)
• Inventors: MORI, Atsushi, MAENO, Katsuhiro, TAKABAYASHI, Naoki, TAJIMA, Kiyoshi
• Granted Patent: US 10,711,879 B2
• Time in Patent Office: Days
• CPC Class Codes: C21D 1/06 Surface hardening
• CPC Class Codes: C21D 9/32 for gear wheels, worm wheels, or the like
• CPC Class Codes: C23C 8/26 of ferrous surfaces
• CPC Class Codes: C23C 8/32 of ferrous surfaces
• CPC Class Codes: C23C 8/80 After-treatment
• CPC Class Codes: F16C 3/02 Shafts; Axles
• CPC Class Codes: F16D 2300/10 Surface characteristics; Details related to material surfaces
• CPC Class Codes: F16H 1/28 with gears having orbital motion
• CPC Class Codes: F16H 2001/327 with orbital gear sets comprising an internally toothed ring gear
• CPC Class Codes: F16H 2055/176 Ring gears with inner teeth
• CPC Class Codes: F16H 48/22 using friction clutches or brakes
• CPC Class Codes: F16H 55/06 Use of materials; Use of treatments of toothed members or worms to affect their intrinsic material properties coatings for lubrication F16H57/041; producing gear wheels from plastics or substances in a plastic state B29D15/00; heat treatment C21D9/32; electrolytic surface treatment C25D; heating by electromagnetic field H05B6/00
• CPC Class Codes: F16H 57/08 of gearings with members having orbital motion

Abstract

A ring gear that, together with a sun gear and a pinion gear that is disposed radially outward of the sun gear and meshes with the sun gear, forms a planetary gear unit, the ring gear includes: a body, internal teeth that are configured to mesh with the pinion gear and that are formed in at least a part of an inner peripheral surface of the body, and external teeth that have a lower hardness than the internal teeth and that are formed in at least a part of an outer peripheral surface of the body, wherein a surface nitrogen concentration in the internal teeth is higher than that in at least tooth surfaces of the external teeth.

Claims

1. A ring gear that, together with a sun gear and a pinion gear that is disposed radially outward of the sun gear and meshes with the sun gear, forms a planetary gear unit, the ring gear comprising:

a body,

internal teeth that are configured to mesh with the pinion gear and that are formed in at least a part of an inner peripheral surface of the body, and

external teeth that have a lower hardness than the internal teeth and that are formed in at least a part of an outer peripheral surface of the body,

wherein a surface nitrogen concentration in the internal teeth is higher than that in at least tooth surfaces of the external teeth.

2. The ring gear according to claim 1, wherein

the external teeth are configured so that a clutch disc can be disposed radially outward of a ring gear mesh with the external teeth.

3. A method for manufacturing a ring gear having internal teeth in an inner peripheral surface and external teeth in a outer peripheral surface from an annular raw blank, comprising the steps of:

forming an intermediate body by forming the internal teeth in an inner peripheral surface of the annular raw blank;

forming a nitride layer at a surface of the intermediate body by nitriding an entirety of the intermediate body;

removing the nitride layer formed in a part of an outer peripheral surface of the intermediate body resulting from the nitriding, which is a part where formation of the external teeth is desired; and

forming the external teeth in a part of the intermediate body from which the nitride layer has been removed and where formation of the external teeth is desired.

4. The method for manufacturing a ring gear according to claim 3, wherein

the outer peripheral surface of the intermediate body resulting from the nitriding is a smooth surface that is even in a circumferential direction.

5. The method for manufacturing a ring gear according to claim 3, wherein

the nitride layer of the ring gear is formed by gas nitrocarburizing.