Strain wave gearing

Patent metadata

Field	Value
Publication number	US-12222028-B2
Application number	US-202118573062-A
Country	US
Kind code	B2
Filing date	Aug 24, 2021
Priority date	Aug 24, 2021
Publication date	Feb 11, 2025
Grant date	Feb 11, 2025

Abstract

In a strain wave gearing, a thrust force applied on an externally toothed gear during an increased-speed operation causes the externally toothed gear to move along an axis in a first direction, and the output-side end surface thereof is pressed, by a prescribed force, against a friction surface of a friction plate integrated with a rotating shaft part of a strain wave generator. Torque transmission efficiency can be reduced only during increased-speed operation, by means of a friction loss occurring between the externally toothed gear and the friction plate. When large load torque is applied from an output shaft which is an output-side member during reduced-speed operation, retention torque of the strain wave generator which is an input-side member during speed-reduction operation can be reduced.

First claim

The invention claimed is:

1. A strain wave gearing comprising:
a first internally toothed gear and a second internally toothed gear that have differing numbers of teeth;
a flexible externally toothed gear that is capable of meshing with the first and second internally toothed gears and has the same number of teeth as the second internally toothed gear; and
a wave generator that causes the externally toothed gear to flex into a non-circular shape and partially mesh with each of the first and second internally toothed gears,
wherein
the strain wave gearing has a friction member provided with a friction surface that is disposed at a position with which the externally toothed gear can come into contact when moving in a first direction, where the first direction is a direction extending from a side of the first internally toothed gear toward a side of the second internally toothed gear along an axis; and
the friction member is attached to a rotating shaft part of the wave generator or is formed integrally with the rotating shaft part so as to rotate integrally with the rotating shaft part and so as not to move relative to the rotating shaft part in the direction of the axis, and
wherein
the strain wave gearing has a restricting member provided with a contact surface that is disposed at a position with which the externally toothed gear can come into contact when moving in a second direction,
where the second direction is a direction extending from the side of the second internally toothed gear toward the side of the first internally toothed gear along the axis,
the contact surface is a surface having a frictional resistance that is lower than that of the friction surface.

2. The strain wave gearing according to claim 1 , wherein
the wave generator is provided with
a wave generator plug that is provided with a non-circular outer peripheral surface, and
a wave generator bearing that is mounted on the non-circular outer peripheral surface; and
the rotating shaft part and the friction member are formed integrally with the wave generator plug.

3. The strain wave gearing according to claim 1 , wherein
the wave generator causes the externally toothed gear to flex into an ellipsoidal shape and mesh with the first and second internally toothed gears;
the friction surface of the friction member is an annular end surface; and
an outside diameter of the friction surface is equal to or greater than a long-axis outside diameter of an end surface of the ellipsoidally flexed externally toothed gear, the end surface being located on a side that comes into contact with the friction surface, and an inside diameter of the friction surface is equal to or less than a short-axis inside diameter of the end surface.

4. The strain wave gearing according to claim 1 , wherein
the friction surface is disposed between a first position and a neutral position, and the contact surface is disposed at a second position,
where the first position is a first-direction position for restricting a permitted movable range of the externally toothed gear in the direction of the axis, the second position is a second-direction position for the same, and the neutral position is an intermediate position between the first and second positions.

Assignees

• Harmonic Drive Systems

Inventors

• Kobayashi Masaru

Classifications

• F16H1/32

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

• F16H49/001 Primary

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