COMPOUND HARMONIC DRIVE

• US 20150075310A1
• Filed: 09/16/2013
• Published: 03/19/2015
• Est. Priority Date: 09/16/2013
• Status: Active Grant

• Current Assignee: Hamilton Sundstrand Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Hamilton Sundstrand Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Lunin, Stepan, Balsiger, Derick
• Granted Patent: US 9,157,517 B2
• Time in Patent Office: Days
• US Class Current: 74/412.R
• CPC Class Codes: F16H 49/001 Wave gearings, e.g. harmonic drive transmissions harmonic drives specially adapted for positioning programme-controlled manipulators B25J9/1025
• CPC Class Codes: Y10T 29/49826 Assembling or joining
• CPC Class Codes: Y10T 74/19642 Directly cooperating gears

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.

Claims

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.