US-12624725-B2 - Bending meshing type gear device

US12624725B2US 12624725 B2US12624725 B2US 12624725B2US-12624725-B2

Abstract

A bending meshing type gear device includes a wave generator and a wave generator bearing disposed between the wave generator and an external gear. The wave generator bearing includes a first rolling element row with first rolling elements aligned in a circumferential direction, a first holder, a second rolling element row offset in an axial direction from the first element row with second rolling elements aligned in the circumferential direction, and a second holder. The first holder includes first pockets accommodating the first rolling elements, each pocket is open toward a side of the second rolling element row in the axial direction. The second holder includes second pockets accommodating the second rolling elements, each pocket is open toward a side of the first rolling element row in the axial direction. A spacer member is disposed between the first and the second rolling element rows.

Inventors

Kazuyoshi Maekawa

Assignees

SUMITOMO HEAVY INDUSTRIES, LTD.

Dates

Publication Date: 20260512
Application Date: 20250516
Priority Date: 20240523

Claims (12)

1 . A bending meshing type gear device comprising: a wave generator; a bending gear bent and deformed by the wave generator; and a wave generator bearing disposed between the wave generator and the bending gear, wherein the wave generator bearing includes a first rolling element row in which a plurality of first rolling elements are aligned in a circumferential direction, a first holder that holds the plurality of first rolling elements, a second rolling element row disposed at a position offset in an axial direction from the first rolling element row, in which a plurality of second rolling elements are aligned in the circumferential direction, and a second holder that holds the plurality of second rolling elements, the first holder includes a plurality of first pockets, each of which accommodates each of the plurality of first rolling elements, the first pocket is open toward a side of the second rolling element row in the axial direction, the second holder includes a plurality of second pockets, each of which accommodates each of the plurality of second rolling elements, the second pocket is open toward a side of the first rolling element row in the axial direction, and a spacer member is disposed between the first rolling element row and the second rolling element row.
2 . The bending meshing type gear device according to claim 1 , wherein the wave generator bearing includes an outer ring that is common to the first rolling element row and the second rolling element row.
3 . The bending meshing type gear device according to claim 2 , wherein the outer ring is fitted to an inner periphery of the bending gear, is flexible, and is bendably deformed via an inner ring of the wave generator bearing, and the first rolling element row and the second rolling element row in association with rotation of the wave generator.
4 . The bending meshing type gear device according to claim 1 , wherein the wave generator bearing includes an inner ring that is common to the first rolling element row and the second rolling element row.
5 . The bending meshing type gear device according to claim 4 , wherein the inner ring is flexible, and is fixed to the wave generator in a state of being bendably deformed into an elliptical shape by being fitted to the wave generator.
6 . The bending meshing type gear device according to claim 1 , wherein the spacer member is disposed to be movable in a radial direction between an outer periphery of an inner ring and an inner periphery of an outer ring.
7 . The bending meshing type gear device according to claim 6 , wherein the spacer member includes an inner diameter having a predetermined clearance with respect to an outer diameter of the inner ring, and an outer diameter having a predetermined clearance with respect to an inner diameter of the outer ring.
8 . The bending meshing type gear device according to claim 1 , wherein the spacer member does not come into contact with any of the first holder and the second holder.
9 . The bending meshing type gear device according to claim 8 , wherein the first holder holds the plurality of first rolling elements to be rotatable around a rotation axis, and is rotatable around the rotation axis together with the first rolling element row, and the second holder holds the plurality of second rolling elements to be rotatable around the rotation axis, and is rotatable around the rotation axis together with the second rolling element row.
10 . The bending meshing type gear device according to claim 9 , wherein the first holder includes a first ring portion disposed on a counter-load side with respect to the first rolling element row, and a plurality of first pillar portions protruding from the first ring portion to a load side in the axial direction, the second holder includes a second ring portion disposed on the load side with respect to the second rolling element row, and a plurality of second pillar portions protruding from the second ring portion to the counter-load side in the axial direction.
11 . The bending meshing type gear device according to claim 10 , wherein the first pillar portions are aligned at an interval in the circumferential direction, and are cantilevered by the first ring portion, and the second pillar portions are aligned at an interval in the circumferential direction, and are cantilevered by the second ring portion.
12 . The bending meshing type gear device according to claim 1 , wherein a grease having a penetration number of 1 or more is disposed between the first rolling element row and the second rolling element row.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to Japanese Patent Application No. 2024-083784, filed on May 23, 2024, which is incorporated by reference herein in its entirety. BACKGROUND Technical Field A certain embodiment of the present invention relates to a bending meshing type gear device. Description of Related Art In the related art, a bending meshing type gear device is known which includes an external gear bent and deformed by a wave generator and a wave generator bearing disposed between the wave generator and the external gear (for example, refer to the related art). In this type of bending meshing type gear device, when the wave generator bearings are arranged in double rows or the like, a space may be secured between two rows of rolling elements, and a lubricant (grease) may be held in the space in some cases. SUMMARY According to an aspect of the present invention, there is provided a bending meshing type gear device including a wave generator, a bending gear bent and deformed by the wave generator, and a wave generator bearing disposed between the wave generator and the bending gear. The wave generator bearing includes a first rolling element row in which a plurality of first rolling elements are aligned in a circumferential direction, a first holder that holds the plurality of first rolling elements, a second rolling element row disposed at a position offset in an axial direction from the first rolling element row, in which a plurality of second rolling elements are aligned in the circumferential direction, and a second holder that holds the plurality of second rolling elements. The first holder includes a plurality of first pockets, each of which accommodates each of the plurality of first rolling elements. The first pocket is open toward a side of the second rolling element row in the axial direction. The second holder includes a plurality of second pockets, each of which accommodates each of the plurality of second rolling elements. The second pocket is open toward a side of the first rolling element row in the axial direction. A spacer member is disposed between the first rolling element row and the second rolling element row. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view illustrating a bending meshing type gear device according to an embodiment. FIG. 2 is an enlarged view of a portion E in FIG. 1. FIG. 3 is a view illustrating a positional relationship between a rolling element row, a holder, and a spacer member in a wave generator bearing according to the embodiment. FIG. 4 is a view illustrating a modification example of the wave generator bearing according to the embodiment, and is a partial sectional view illustrating the same portion as that in FIG. 3. DETAILED DESCRIPTION However, when only the space between the rolling element rows is simply filled with the lubricant, the lubricant may remain in the space, and the rolling elements may not be preferably lubricated in some cases. It is desirable to preferably lubricate a wave generator bearing. Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Configuration of Bending Meshing Type Gear Device FIG. 1 is a sectional view illustrating a bending meshing type gear device 1 according to the present embodiment. Hereinafter, a direction along a rotary axis O1 in the drawing is defined as an “axial direction”, a direction perpendicular to the rotary axis O1 is defined as a “radial direction”, and a rotation direction around the rotary axis O1 is defined as a “circumferential direction”. In addition, in the axial direction, a side connected to an external driven member E (left side in the drawing) will be referred to as a “load side”, and a side opposite to the load side (right side in the drawing) will be referred to as a “counter-load side”. As illustrated in FIG. 1, the bending meshing type gear device 1 is a tubular bending meshing type gear device in which an external gear 12 is bent and deformed to transmit a rotating motion around the rotary axis O1. Specifically, the bending meshing type gear device 1 includes a wave generator shaft 10, an external gear 12 bent and deformed by the wave generator shaft 10, a first internal gear 22g and a second internal gear 23g which mesh with the external gear 12, and a wave generator bearing 15. In addition, the bending meshing type gear device 1 includes a first casing 22, an internal gear member 23, a second casing 24, a first cover 26, a second cover 27, and a main bearing 33. The wave generator shaft 10 has a hollow shaft shape, and includes a wave generator 10a having an elliptical outer shape (outer periphery) in a cross section perpendicular to the rotary axis O1 (having a major axis and a minor axis which are perpendicular to each other), and shaft portions 10b and 10c provided on both sides of the wave generator 10a in the axial direction and having a circular outer shape in a cross-sect