Compound harmonic drive

Patent metadata

Field	Value
Publication number	US-9157517-B2
Application number	US-201314027788-A
Country	US
Kind code	B2
Filing date	Sep 16, 2013
Priority date	Sep 16, 2013
Publication date	Oct 13, 2015
Grant date	Oct 13, 2015

Abstract

A harmonic drive includes a first flexible gear and a second flexible gear disposed around the first flexible gear and coaxial with the first flexible gear. A first ring gear meshes with the first flexible gear, and a second ring gear meshes with the second flexible gear.

First claim

The invention claimed is:

1. A harmonic drive comprising:
a first flexible gear;
a second flexible gear disposed around the first flexible gear and coaxially with the first flexible gear;
a first ring gear that meshes with the first flexible gear; and
a second ring gear that meshes with the second flexible gear.

2. The harmonic drive of claim 1 , wherein the first flexible gear is axially wider than the second flexible gear.

3. The harmonic drive of claim 2 , wherein the second flexible gear is concentric with the first flexible gear, and the second flexible gear includes radially-inward-extending teeth that mate with radially-outward-extending teeth of the first flexible gear such that the second flexible gear does not rotate relative the first flexible gear.

4. The harmonic drive of claim 3 , wherein the first ring gear is disposed around a portion of the first flexible gear and includes radially-inward-extending teeth that mesh with the radially-outward extending teeth of the first flexible gear.

5. The harmonic drive of claim 4 , wherein the second ring gear is disposed around the second flexible gear and includes radially-inward-extending teeth that mesh with radially-outward-extending teeth of the second flexible gear.

6. The harmonic drive of claim 5 , wherein the second flexible gear includes a different number of radially-outward-extending teeth than the first flexible gear.

7. The harmonic drive of claim 5 , wherein the second ring gear includes a different number of radially-inward-extending teeth than the first ring gear.

8. The harmonic drive of claim 5 further comprising:
a third ring gear disposed around another portion of the first flexible gear and includes radially-inward-extending teeth that mesh with the radially-outward-extending teeth of the first flexible gear.

9. The harmonic drive of claim 8 , wherein the third ring gear includes the same number of radially-inward-extending teeth as the first ring gear.

10. The harmonic drive of claim 5 further comprising:
a wave generator disposed radially within the first flexible gear and the second flexible gear and engaged with both the first and second flexible gears, the wave generator comprising:
a plug with an elliptical cross-section;
a shaft extending from the plug;
a bearing race disposed around the plug; and
bearings disposed between the bearing race and the first flexible gear; and

wherein the wave generator rotates both the first flexible gear and the second flexible gear as the wave generator rotates.

11. The harmonic drive of claim 1 , wherein the wave generator rotates both the first flexible gear and the second flexible gear at the same rate.

12. The harmonic drive of claim 1 , wherein the first flexible gear and the second flexible gear are integral.

13. The harmonic drive of claim 1 , wherein the first ring gear or the second ring gear is grounded.

14. A method of assembling a harmonic drive, the method comprising:
positioning a wave generator radially within a first flexible gear, the first flexible gear comprising radially-outward-extending teeth;
positioning a second flexible gear around the first flexible gear such that the second flexible gear and the first flexible gear are coaxial, the second flexible gear comprising radially-outward-extending teeth, an axial width smaller than an axial width of the first flexible gear, and radially-inward-extending teeth that mate with the radially-outward-extending teeth of the first flexible gear;
positioning a first ring gear around a portion of the first flexible gear such that radially-inward-extending teeth of the first ring gear mesh with the radially-outward-extending teeth of the first flexible gear; and
positioning a second ring gear around the second flexible gear such that radially-inward-extending teeth of the second ring gear mesh with the radially-outward-extending teeth of the second flexible gear.

15. The method of claim 14 , the method further comprising:
connecting the first ring gear to ground; and
connecting the second ring gear to an output structure.

Assignees

• Hamilton Sundstrand Corp

Inventors

• Lunin Stepan
• Balsiger Derick

Classifications

• F16H49/001 Primary

  Wave gearings, e.g. harmonic drive transmissions · CPC title

• Y10T29/49826

  Assembling or joining · CPC title

• Y10T74/19642

  Directly cooperating gears · CPC title