Powder lubrication method of strain wave gearing

Patent metadata

Field	Value
Publication number	US-12092199-B2
Application number	US-202117998573-A
Country	US
Kind code	B2
Filing date	Aug 24, 2021
Priority date	Aug 24, 2021
Publication date	Sep 17, 2024
Grant date	Sep 17, 2024

Abstract

A powder supply mechanism, which is provided with a press-molded article obtained by consolidating a solid lubricant powder in advance, is incorporated into an inner-side space of an externally toothed gear of a strain wave gearing. While the strain wave gearing is operating, the press-molded article is worn down by the friction plate, whereby the powder supply mechanism can incrementally supply very small amounts of a solid lubricant abrasion powder from the press-molded article over an extended period. It is possible to suppress any reduction in efficiency caused by loss torque produced due to a large amount of the solid lubricant powder infiltrating gaps in, inter alia, a contact section of a wave generator rotating at high speed. Thus, it is possible to extend the service life of the powder-lubricated strain wave gearing while keeping the efficiency consistently high.

First claim

The invention claimed is:

1. A powder lubrication method of a strain wave gearing, comprising:
disposing a press-molded article of a solid lubricant powder inside a strain wave gearing;
making a friction plate to bring into frictional contact with the press-molded article to produce a solid lubricant abrasion powder while the strain wave gearing is operating; and
using the produced solid lubricant abrasion powder to lubricate sites to be lubricated in the strain wave gearing.

2. The powder lubrication method of a strain wave gearing according to claim 1 , wherein
the solid lubricant powder is at least one from among molybdenum disulfide, tungsten disulfide, graphite, carbon nanotubes, and onion-like carbon.

3. The powder lubrication method of a strain wave gearing according to claim 1 , wherein
the press-molded article is a lightly press-molded article having a compacting density of equal to or less than 50% of the true density.

4. The powder lubrication method of a strain wave gearing according to claim 1 , wherein:
the material of the friction plate is steel, stainless steel, a copper alloy, an aluminum alloy, or a ceramic, said material having a hardness of Hv 60 or greater, or a Mohs hardness of 2 or greater; and
the surface roughness of a friction surface of the friction plate is equal to or less than 12S.

5. The powder lubrication method of a strain wave gearing according to claim 1 , wherein:
the strain wave gearing is provided with a rigid internally toothed gear, a flexible externally toothed gear disposed inside the internally toothed gear, and a wave generator disposed inside the externally toothed gear;
the wave generator is a rotation-inputting member, and the externally toothed gear is a secured member or a rotation-outputting member;
the friction plate is attached to one element from among the wave generator and the externally toothed gear, and the press-molded article is attached to the other of these elements; and
at least one component from among the friction plate and the press-molded article is pressed against the other of these components using a spring member, whereby a state of frictional contact between these elements is maintained.

6. A strain wave gearing comprising:
a rigid internally toothed gear,
a flexible externally toothed gear disposed inside the internally toothed gear,
a wave generator disposed inside the externally toothed gear, and
a powder supply mechanism disposed inside the externally toothed gear,
the powder supply mechanism being provided with
a press-molded article of a solid lubricant powder,
a friction plate that comes into frictional contact with the press-molded article to produce a solid lubricant abrasion powder, and
a spring member for pressing the friction plate against the press-molded article and maintaining the state in which these two elements are in frictional contact.

7. The strain wave gearing according to claim 6 , wherein
the solid lubricant powder is at least one from among molybdenum disulfide, tungsten disulfide, graphite, carbon nanotubes, and onion-like carbon.

8. The strain wave gearing according to claim 6 , wherein:
the wave generator is a rotation-inputting member, and the externally toothed gear is a secured member or a rotation-outputting member;
the friction plate is disposed on one element from among the wave generator and the externally toothed gear, and the press-molded article is disposed on the other of these elements; and
at least one component from among the friction plate and the press-molded article is pressed against the other of these components using the spring member.

9. The strain wave gearing according to claim 6 , wherein
the press-molded article is a lightly press-molded article having a compacting density of no more than 50% of the true density.

10. The strain wave gearing according to claim 6 , wherein
the press-molded article is cylindrical or annular.

11. The strain wave gearing according to claim 6 , wherein:
the material of the friction plate is steel, stainless steel, a copper alloy, an aluminum alloy, or a ceramic, said material having a hardness of Hv 60 or greater, or a Mohs hardness of 2 or greater; and
the surface roughness of a friction surface of the friction plate is 12S or less.

Assignees

• Harmonic Drive Systems

Inventors

• Kobayashi Masaru

Classifications

• F16H57/048

  Type of gearings to be lubricated, cooled or heated · CPC title

• F16H49/001

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

• F16H57/041 Primary

  Coatings or solid lubricants, e.g. anti-seize layers or pastes · CPC title

• F16H57/0486

  with fixed gear ratio  (axle or inter-axle differentials F16H57/0483) · CPC title

• F16H57/0479 Primary

  Gears or bearings on planet carriers · CPC title