# US 8,770,064 B2 · Wave generator for wave gear device

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- Number: US 8,770,064 B2
- Document ID: US8770064B2
- Status: Granted
- Kind: B2
- Application number: 13/616,318
- Filed: 2012-09-14
- Published: 2013-03-28
- Granted: 2014-07-08
- Earliest claimed: 2009-01-13
- Assignees: Harmonic Drive Systems Inc.
- Applicants: Xin Yue Zhang; Toshimi Yamagishi; Keiji Ueura
- Inventors: Xin Yue Zhang; Toshimi Yamagishi; Keiji Ueura
- Web page: https://patentgrep.com/patent/US8770064B2

## CPC

- F16H 1/321: {the orbital gear being nutating}
- F16C 19/06: with a single row or balls
- F16C 27/04: Ball or roller bearings, e.g. with resilient rolling bodies
- F16C 33/585: {of raceways, e.g. ribs to guide the rollers}
- F16H 49/001: {Wave gearings, e.g. harmonic drive transmissions}
- F16C 2240/40: Linear dimensions, e.g. length, radius, thickness, gap
- F16C 2361/61: Toothed gear systems, e.g. support of pinion shafts
- Y10T 74/19: Gearing
- F16H: GEARING
- F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

The flexible bearing of the wave generator for a wave gear device is a deep-groove ball bearing in which an outer race and an inner race form an annular flexible bearing ring capable of bending in a radial direction. A ball diameter Da is set to be 5 to 15% greater than that of each model of the currently available product. Dimensions of orbital plane radii ro, ri of the inner and outer races are set so that the ratio ro/Da of the orbital plane radius ro of the inner race and the ball diameter Da, as well as the ratio ri/Da of the orbital plane radius ri of the outer race and the ball diameter Da, are both in the range of 0.51 to 0.52. With this configuration, the service life of the flexible bearing can be extended.

## Claims

### Claim 1

A wave generator for a wave gear device wherein a flexible externally toothed gear disposed inside an annular rigid internally toothed gear is bent into a non-circular shape and caused to partially mesh with the rigid internally toothed gear to move the meshing positions of the two toothed gears in a circumferential direction and to generate relative rotation between the toothed gears brought about by a difference in the number of teeth of the two toothed gears, comprising:
a rigid plug; and
an annular flexible bearing bent into a non-circular shape by a non-circular external circumferential surface of the rigid plug;
wherein the flexible bearing is a deep-groove ball bearing having an annular flexible outer race and flexible inner race capable of bending in a radial direction;
wherein pitch circle diameters PCD of the flexible externally toothed gear of each model of the wave gear device are set as shown in Table below, and the ball diameters Da of the flexible bearing are set as shown in the Table according to each model of the wave gear device; and
wherein dimensions of orbital plane radii ro, ri of the inner and outer races are set so that the ratio ro/Da of the orbital plane radius ro of the inner race and the ball diameter Da, as well as the ratio ri/Da of the orbital plane radius ri of the outer race and the ball diameter Da, are both in the range of 0.51 to 0.52 in each model of the wave gear device as shown in the Table:
TABLE
PCD (mm) of
Flexible
Ball
Model
Externally
Diameter
No.
Toothed Gear
Da (mm)
ro/Da
ri/Da
8
20.320
2.1-2.3
0.51-0.52
0.51-0.52
11
28.22
2.5-2.7
14
34.925
3.3-3.7
17
43.180
4.2-4.6
20
50.800
5.0-5.5
25
63.500
5.8-6.4
32
82.550
7.5-8.2
40
101.600
10.0-10.9
45
114.300
11.5-12.6
50
127.00
12.5-13.7
58
147.320
14.2-15.5
65
165.100
15.0-16.4
80
203.200
20.0-21.9
90
228.600
22.5-24.6
100
254.00
25.0-27.4.

### Claim 2 (depends on 1)

The wave generator for a wave gear device according to claim 1, wherein
the rigid plug comprises an elliptical external circumferential surface; and
the flexible bearing is bent into an elliptical shape.