# US 10,480,619 B2 · Ring gear, gear device and mold for manufacturing the ring gear

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- Number: US 10,480,619 B2
- Document ID: US10480619B2
- Status: Granted
- Kind: B2
- Application number: 15/660,321
- Filed: 2017-07-26
- Published: 2018-02-22
- Granted: 2019-11-19
- Earliest claimed: 2016-08-22
- Assignees: Johnson Electric International AG
- Applicants: Johnson Electric International AG
- Inventors: Jing Ning Ta; Lap Wah Lo; Xing Ju Yi; Qiu Mei Li
- Web page: https://patentgrep.com/patent/US10480619B2

## CPC

- F16H 1/46: Systems consisting of a plurality of gear trains each with orbital gears, {i.e. systems having three or more central gears}
- B21J 5/025: {Closed die forging}
- B21K 1/30: with gear-teeth
- B21K 1/305: {helical}
- B22F 3/03: Press-moulding apparatus therefor
- B22F 5/08: of toothed articles, e.g. gear wheels; of cam discs
- F16H 55/17: Toothed wheels (worm wheels F16H55/22; chain wheels F16H55/30)
- F16H 57/08: of gearings with members having orbital motion
- F16H 2055/176: {Ring gears with inner teeth}
- F16H: GEARING
- B21J: FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES (rolling of metal B21B; making particular products by forging or pressing B21K; cladding or plating B23K; finishing surfaces by hammering B23P9/04; compacting surfaces by blasting with particulate material B24C1/10; general features of presses, presses for consolidating scrap B30B; furnaces in general F27)
- B21K: MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS (making particular articles by working sheet metal without essentially removing material B21D; processing wire B21F; making pins, needles or nails B21G; making particular articles by rolling B21H; forging machines, pressing machines, hammering machines, in general B21J; making chains B21L; plating B23K)
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER

## Abstract

The present invention provides a ring gear and a gear reduction device. The ring gear includes a one-piece annular body made from powder metallurgy material, and a first ring gear part and a second ring gear part formed on a surface of the annular body. The first ring gear part and the second ring gear part are arranged along an axial direction of the annular body. The ring gear has a density that is less than 92% of its theoretical density and in the range of 6.0 to 8.0 grams per cubic centimeter. The present invention further provides a mold for manufacturing the ring gear. The ring gear of the present invention includes two ring gears integrally formed at once, and the two ring gears have improved concentricity.

## Claims

### Claim 1

A gear device comprising:
a first planetary gear train including a first sun gear, a first planetary gear set surrounding the first sun gear, and a first carrier that is driven by revolution of the first planetary gear set about the first sun gear;
a second planetary gear train including a second sun gear, a second planetary gear set surrounding the second sun gear, and a second carrier that is driven by revolution of the second planetary gear set about the second sun gear;
a ring gear comprising a first ring gear part that comprises a first annular body and a plurality of first teeth formed on a surface of the first annular body; and a second ring gear part that comprises a second annular body and a plurality of second teeth formed on a surface of the second annular body; wherein the first ring gear part and the second ring gear part are integrally formed from powder metal, the ring gear has a density that is less than 92% of its theoretical density and in a range of 6.0 to 8.0 grams per cubic centimeter; and
a flange mounted to an end of the ring gear, wherein the flange comprises a flange body abutting the end of the ring gear, and a connecting portion extending from the flange body and being inserted into inside of the ring gear, and the connecting portion has a round circumferential surface configured to contact with tips of the teeth of the ring gear;
the first planetary gear train and the second planetary gear train disposed within the ring gear, each planetary gear of the first planetary gear set meshing with both of the first sun gear and the first teeth of the ring gear, and each planetary gear of the second planetary gear set meshing with both of the second sun gear and the second teeth of the ring gear.

### Claim 2 (depends on 1)

The gear device of claim 1, wherein one of the first annular body and the second annular body forms a plurality of recessed mounting portions, the connecting portion forms a plurality of engaging portions protruding from an outer circumferential surface thereof, and the protruding engaging portions are respectively received in the recessed mounting portions.