US 11,982,343 B2
Strain wave gearing having roller-bearing-type wave generator
Masaru Kobayashi, Azumino (JP)
Assigned to HARMONIC DRIVE SYSTEMS INC., Tokyo (JP)
Appl. No. 17/052,343
Filed by HARMONIC DRIVE SYSTEMS INC., Tokyo (JP)
PCT Filed May 17, 2019, PCT No. PCT/JP2019/019787
§ 371(c)(1), (2) Date Nov. 2, 2020,
PCT Pub. No. WO2020/234945, PCT Pub. Date Nov. 26, 2020.
Prior Publication US 2023/0116162 A1, Apr. 13, 2023
Int. Cl. F16H 49/00 (2006.01); F16C 19/26 (2006.01)
CPC F16H 49/001 (2013.01) [F16C 19/26 (2013.01); F16H 2049/003 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A strain wave gearing, comprising:
a rigid internally toothed gear;
a flexible externally toothed gear disposed concentrically on an inner side of the internally toothed gear; and
a wave generator disposed concentrically on an inner side of the externally toothed gear, to cause the externally toothed gear to flex into an ellipsoidal shape and partially mesh with the internally toothed gear,
wherein
the externally toothed gear is provided with:
a cylindrical barrel part capable of flexing in a radial direction;
a diaphragm extending radially outward or inward from one end of the cylindrical barrel part;
external teeth formed in an externally peripheral surface portion at a side having another end of the cylindrical barrel part,
wherein
the wave generator is provided with:
a plug having an ellipsoidal external peripheral surface for flexing the cylindrical barrel part, where the external teeth are formed, into an ellipsoidal shape; and
a roller bearing that is mounted between the ellipsoidal external peripheral surface of the plug and an internal peripheral surface of the cylindrical barrel part of the externally toothed gear and that supports the externally toothed gear so as to allow rotation relative to the plug,
the roller bearing being provided with rollers having a cup shape,
the plug being formed with a recess extending in an annular shape or an ellipsoidal shape proximate the ellipsoidal external peripheral surface, and
wherein
end surfaces of the plug on both sides in a plug axis direction are designated as first and second end surfaces,
the recess opens on the first end surface, which faces toward a side of the diaphragm of the externally toothed gear; and
the recess has a predetermined width in a radial direction of the plug and a predetermined depth from the first end surface toward the second end surface, whereby a radial-direction rigidity of the plug is lower in a side having the first end surface onto which the recess opens than in a side having the second end surface, and
the rollers are aligned so that an open end of the cup shape thereof faces toward the diaphragm of the externally toothed gear.