Inverted compound harmonic drive

Patent metadata

Field	Value
Publication number	US-11085518-B2
Application number	US-201916388603-A
Country	US
Kind code	B2
Filing date	Apr 18, 2019
Priority date	Apr 18, 2019
Publication date	Aug 10, 2021
Grant date	Aug 10, 2021

Abstract

An inverted compound harmonic drive including: a wave generator configured to receive rotational input; a flex spline disposed radially within the wave generator that receives energy due to the rotation of the wave generator, the flex spline including a plurality of inner facing splines that include an axial center spline, a first axial end spline being adjacent to and forward of the axial center spline, and a second axial end spline adjacent to and aft of the axial center spline; an output gear meshes with the axial center spline; a first ground gear adjacent to and forward of the output gear that meshes with the first axial end spline; and a second ground gear adjacent to an aft of the output gear that meshes with the second axial end spline.

First claim

What is claimed is:

1. An inverted compound harmonic drive comprising:
a wave generator configured to receive rotational input;
a flex spline disposed radially within the wave generator that receives energy due to the rotation of the wave generator, the flex spline including a plurality of inner facing splines that include an axial center spline, a first axial end spline being adjacent to and forward of the axial center spline, and a second axial end spline adjacent to and aft of the axial center spline;
an output gear meshes with the axial center spline;
a first ground gear adjacent to and forward of the output gear that meshes with the first axial end spline; and
a second ground gear adjacent to an aft of the output gear that meshes with the second axial end spline;
wherein:
the first ground gear includes a first ground shaft extending in a forward direction;
the second ground gear includes a second ground shaft extending in an aft direction; and
the output gear includes an output shaft, the output shaft including one or more of:
a first shaft portion extending in the forward direction with a first passage therethrough, the first passage being splined; and
a second shaft portion extending in the aft direction with a second passage therethrough, the second passage being continuous with the first passage, second passage being splined.

2. The drive of claim 1 , wherein:
the first axial end spline and the first ground gear have a first gear ratio;
the second axial end spline and the second ground gear have a second gear ratio that is the same as the first gear ratio; and
the axial center spline and the output gear have a third gear ratio that differs from the first and second gear ratios.

3. The drive of claim 1 , wherein:
the first ground shaft has a third passage therethrough with a third passage diameter;
the second ground shaft has a fourth passage therethrough with a fourth passage diameter;
the first shaft portion of the output shaft extends through the third passage; and
the second shaft portion of the output shaft extends through the fourth passage.

4. The drive of claim 1 , wherein the first ground shaft and the second ground shaft each include a plurality of mounting holes.

5. The drive of claim 1 , further comprising:
a first axial end bearing disposed between the first ground shaft and the wave generator;
a second axial end bearing disposed between the second ground shaft and the wave generator; and
an axial center bearing disposed between the flex spline and the wave generator.

6. The drive of claim 5 , wherein:
the first axial end bearing and the second axial end bearing are roller bearings, ball bearings or a plain bearings; and
the axial center bearing is a roller bearing, a ball bearing or a plain bearing.

7. The drive of claim 5 , further comprising:
a first retaining ring disposed between the first axial end bearing and the axial center bearing and against the first axial end bearing;
a first thrust washer disposed between the first axial end bearing and the axial center bearing and against the axial center bearing;
a second retaining ring between the second axial end bearing and the axial center bearing and against the second axial end bearing; and
a second thrust washer between the second axial end bearing and the axial center bearing and against the axial center bearing.

8. An aircraft system comprising:
an inverted compound harmonic drive that includes:
a wave generator receives rotational input from a first aircraft component;
a flex spline disposed radially within the wave generator that receives energy due to the rotation of the wave generator, the flex spline including a plurality of inner facing splines that include an axial center spline, a first axial end spline being adjacent to and forward of the axial center spline, and a second axial end spline being adjacent to and aft of the axial center spline;
an output gear meshes with the axial center spline;
a first ground gear is adjacent to and forward of the output gear and meshes with the first axial end spline; and
a second ground gear is adjacent to and aft of the output gear and meshes with the second axial end spline,
wherein:
the first ground gear includes a first ground shaft extending in a forward direction and connecting with aircraft ground structure;
the second ground gear includes a second ground shaft extending in an aft direction and connecting with aircraft ground structure; and
the output gear includes an output shaft, the output shaft including one or more of,
a first shaft portion extending in the forward direction with a first passage therethrough, the first passage being splined; and
a second shaft portion extending in the aft direction with a second passage therethrough, the second passage being continuous with the first passage, first passage being splined;
wherein the output shaft is configured to connect with a second aircraft component.

9. The system of claim 8 , wherein:
the first axial end spline and the first ground gear are configured with a first gear ratio; and
the second axial end spline and the second ground gear are configured with a second gear ratio that is the same as the first gear ratio; and
the axial center spline and the output gear are configured with a third gear ratio that differs from the first gear ratio.

10. The system of claim 8 , wherein:
the first ground shaft has a third passage therethrough with a third passage diameter;
the second ground shaft has a fourth passage therethrough with a fourth passage diameter;
the first shaft portion of the output shaft extends through the third passage; and
the second shaft portion of the output shaft extends through the fourth passage.

11. The system of claim 8 , wherein the first ground shaft and the second ground shaft each include a plurality of mounting holes.

12. The system of claim 8 , comprising:
a first axial end bearing disposed between the first ground shaft and the wave generator;
a second axial end bearing disposed between the second ground shaft and the wave generator; and
an axial center bearing disposed between the flex spline and the wave generator.

13. The system of claim 12 , wherein:
the first axial end bearing and the second axial end bearing are roller bearings, ball bearings or a plain bearings; and
the axial center bearing is a roller bearing, a ball bearing or a plain bearing.

14. The system of claim 12 , wherein:
a first retaining ring and a first thrust washer are disposed between the first axial end bearing and the axial center bearing, wherein the first retaining ring is against the first axial end bearing and the first thrust washer is against the axial center bearing; and
a second retaining ring and a second thrust washer are disposed between the second axial end bearing and the axial center bearing, wherein the second retaining ring is against the second axial end bearing and the second thrust washer is against the axial center bearing.

15. A method of transmitting energy from a first component to a second component, comprising:
coupling an inverted compound harmonic drive to the first component, the second component, and a ground structure;
transmitting energy from the first component to a wave generator of the inverted compound harmonic drive;
transmitting energy from the wave generator to a flex spline of the inverted compound harmonic drive; and
transmitting energy from the flex spline to:
an output gear that meshes with an axial center spline of the flex spline;
a first ground gear is adjacent to and forward of the output ge

Assignees

• Hamilton Sundstrand Corp
• Hamilton Sunstrand Corp

Inventors

• Balsiger Derick S
• Bloxham Keith

Classifications

• F16H49/001 Primary

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

• B64C13/28

  mechanical · CPC title

• F16H2049/003

  Features of the flexsplines therefor · CPC title