Bearing Retainer Structure for Dense Rolling Element Layouts

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Solution Overview

Problem

Existing bearings used in speed reducers face challenges in securing sufficient strength and rigidity due to the reduction in gap between adjacent rolling elements when increasing the number of rolling elements to improve durability.

Innovation Solution

The bearing design includes an annular retainer with column portions and flange portions that extend radially outside the rolling elements, securing the thickness of the column portions between adjacent elements, enhancing the retainer's strength and rigidity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If the number of rolling elements is increased to improve durability, then the durability is improved, but the gap between adjacent rolling elements is reduced, making it difficult to secure sufficient strength of the retainer

Engineering Contradiction:
ImprovedurabilityVSAvoidretainer strength
Core Design Contradiction:
Duration of action of moving objectVSStrength

Solution Approach 1:

The column portions are positioned radially outside the rolling elements rather than between them in the circumferential direction. This spatial repositioning in the radial dimension allows the column portions to maintain sufficient thickness even when the gap between rolling elements is reduced, thereby preserving retainer strength while enabling increased rolling element count for improved durability

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Duration of action of moving object

If the gap between adjacent rolling elements is reduced to accommodate more rolling elements, then the durability is improved, but the thickness of the retainer at the gap location is reduced, compromising the retainer's strength

Engineering Contradiction:
ImprovedurabilityVSAvoidretainer thickness
Core Design Contradiction:
Duration of action of moving objectVSLength of moving object

Solution Approach 1:

The column portions are positioned radially outside the rolling elements rather than between them in the circumferential direction. This spatial repositioning in the radial dimension allows the column portions to maintain sufficient thickness even when the gap between rolling elements is reduced, thereby preserving retainer strength while enabling increased rolling element count for improved durability

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP4421337B1Bearing, speed reducer, and robot
Publication Date: 2025.12.03 NIDEC DRIVE TECH CORP
  • EP4421337B1 patent drawingFigure 1
  • EP4421337B1 patent drawingFigure 2
  • EP4421337B1 patent drawingFigure 3

AI summary

A bearing (85) includes an inner ring (41), an outer ring (42), an annular retainer (43), and a plurality of rolling elements (44). The inner ring (41) is disposed radially outside a central axis. The outer ring (42) is disposed radially outside the inner ring (41). The retainer (43) is disposed between the inner ring (41) and the outer ring (42). The plurality of rolling elements (44) are arranged at intervals in the circumferential direction by the retainer (43) between the inner ring (41) and the outer ring (42). The retainer (43) includes a plurality of column portions (431) and a flange portion (432). The column portion (431) is disposed between the adjacent rolling elements (44). The flange portion (432) connects end portions on one axial side of the plurality of column portions (431) in the circumferential direction. The flange portion (432) extends radially inside from an end portion on one axial side of the column portion (431). In a transverse plane passing through the radial center of the rolling element (44) and orthogonal to the central axis, the radial center of the column portion (431) is disposed radially outside the radial center of the rolling element (44). The other axial end of the flange portion (432) is disposed on the other axial side with respect to the one axial end of the rolling element (44).