Strain wave gearing

Patent metadata

Field	Value
Publication number	US-12215768-B2
Application number	US-202318164856-A
Country	US
Kind code	B2
Filing date	Feb 6, 2023
Priority date	Aug 2, 2022
Publication date	Feb 4, 2025
Grant date	Feb 4, 2025

Abstract

In a strain wave gearing, both of a pulley for transmitting rotation in a direction orthogonal to a rotation central axis and an output shaft are arranged on an axial-direction first side relative to a cup-shaped externally toothed gear. The input shaft, which transmits input rotation from the pulley to the wave generator, functions as a support shaft for both the pulley and the wave generator and is supported at both ends by the first and second bearings. A mechanism for transmitting rotation from the pulley to the wave generator, and a mechanism for supporting the rotation-transmitting mechanism, can be made compact, and support strength can also be ensured.

First claim

The invention claimed is:

1. A strain wave gearing provided with a rotation-transmitting member for transmitting rotation in a direction orthogonal to a rotation central axis, the strain wave gearing comprising:
a rigid internally toothed gear;
a flexible externally toothed gear arranged coaxially inside the internally toothed gear, the externally toothed gear being cup-shaped and being capable of flexing in a radial direction;
a wave generator fitted inside the externally toothed gear, the wave generator causing the externally toothed gear to flex into a non-circular shape and partially mesh with the internally toothed gear;
an input shaft extending coaxially from the wave generator toward a first side, which is one side in an axial direction that follows the rotation central axis;
an output shaft coaxially attached from the first side in the axial direction to a boss defining a central portion of a bottom section of the cup shape of the externally toothed gear;
a cover plate attached to the internally toothed gear from a second side, which is opposite from the first side in the axial direction, the cover plate covering the internally toothed gear, the externally toothed gear, and the wave generator from the second side, and
a first bearing and a second bearing for rotatably supporting the input shaft,
wherein
the input shaft is provided with a shaft end section extending from the wave generator and a shaft distal-end section extending from the shaft end section toward the first side through a central through hole formed in the boss;
the rotation-transmitting member is provided with a shaft part protruding toward the second side, and a central hole formed in the shaft part opening toward the second side;
the shaft distal-end section of the input shaft is fitted coaxially into the central hole of the shaft part of the rotation-transmitting member;
the shaft end section of the input shaft is rotatably supported by the boss of the externally toothed gear via the first bearing positioned between the wave generator and the boss in the axial direction; and
the shaft distal-end section of the input shaft is rotatably supported by the output shaft via the second bearing, the second bearing being mounted between the shaft part of the rotation-transmitting member and the output shaft, and the output shaft, the second bearing and the shaft part of the rotation-transmitting member being disposed concentrically in the radial direction.

2. The strain wave gearing according to claim 1 , further comprising a main bearing for supporting the internally toothed gear and the externally toothed gear in a state that allows relative rotation, wherein:
the main bearing is arranged on the first side relative to the internally toothed gear;
an outer race of the main bearing is coaxially attached to the internally toothed gear; and
the output shaft is coaxially attached to an inner race of the main bearing, or the output shaft is formed integrally with the inner race.

3. The strain wave gearing according to claim 1 , further comprising:
a wave washer positioned between the rotation-transmitting member fixed to the input shaft and the output shaft fixed to the boss of the externally toothed gear,
wherein
the wave washer applies axial-direction precompression for absorbing axial-direction rattling of the wave generator.

4. The strain wave gearing according to claim 1 , further comprising a first bearing holder, wherein:
the first bearing holder is coaxially attached to the boss of the externally toothed gear from the second side, and
the first bearing is mounted between the first bearing holder and the shaft end section of the input shaft.

5. The strain wave gearing according to claim 1 , further comprising:
a bearing mounting surface formed on an outer peripheral surface of the rotation-transmitting member; and
a second bearing holder coaxially attached to the output shaft from the first side, wherein
the second bearing is mounted between the bearing mounting surface and the second bearing holder.

6. The strain wave gearing according to claim 1 , further comprising:
a bearing mounting surface formed on a circular outer peripheral surface of the shaft part; and
a bearing holder disposed radially inside the output shaft and fastened coaxially to the output shaft,
the second bearing being mounted between the bearing mounting surface and the bearing holder in the radial direction.

Assignees

• Harmonic Drive Systems

Inventors

• Furuta Kazumasa
• Tanioka Nozomu
• Handa Jun

Classifications

• F16C35/07

  Fixing them on the shaft or housing with interposition of an element · CPC title

• F16C19/04

  for radial load mainly · CPC title

• F16H55/56

  of which the bearing parts are relatively axially adjustable · CPC title

• F16H1/32

  in which the central axis of the gearing lies inside the periphery of an orbital gear · CPC title

• F16H37/041

  for conveying rotary motion with constant gear ratio · CPC title