Outer Ring-Guided Resin Cage for Stable Eccentric Ball Bearings

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Solution Overview

Problem

Ball bearings with crown-shaped resin cages used on eccentric shafts face issues of high surface pressure contact and cage tilting due to centrifugal force, leading to lubricant film breakdown, cage breakage, and increased frictional torque.

Innovation Solution

A ball bearing design using an outer ring-guided crown-shaped resin cage with sliding contact surfaces and guiding protrusions to prevent high surface pressure contact and cage tilting, supported by both outer ring groove shoulders to maintain stability during eccentric rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a ball-guided type of cage is used, then the cage structure is simple, but the cage comes into contact with only some balls with high surface pressure, causing oil film breakdown and cage breakage

Engineering Contradiction:

Improvecage structureVSAvoidcage durability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The cage is divided into multiple guiding protrusions that contact different balls separately, distributing the load across multiple contact points rather than concentrating it on a single guiding surface. This segmentation prevents high surface pressure on any single ball-cage interface.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cage incorporates specific local features (guiding protrusions with rounded surfaces) at strategic positions to create localized low-pressure contact zones. These localized quality improvements prevent oil film breakdown at critical contact points while maintaining overall cage simplicity.

Inventive Principle:

Principle #3Local quality

2Stability of the object's composition

If an outer ring-guided type of cage is used, then the cage is supported by outer ring groove shoulders, but the outer peripheries of pillars come into edge abutment with the intersection ridge, causing increased frictional torque

Engineering Contradiction:

Improvecage stabilityVSAvoidfrictional torque

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

Instead of having the cage outer periphery contact the outer ring groove shoulder directly (which causes edge abutment), the invention inverts the guiding mechanism by using inwardly directed guiding protrusions that contact the outer ring raceway groove. This reverses the contact geometry to eliminate edge abutment and reduce frictional torque.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The guiding protrusions are designed with rounded surfaces that match the curvature of the outer ring raceway groove. This curved contact geometry replaces the sharp edge abutment between flat pillar peripheries and the intersection ridge, significantly reducing frictional torque and wear.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Weight of moving object

If a crown-shaped resin cage is used, then the ball bearing has light weight and low noise, but the cage tilts due to centrifugal force during eccentric rotation

Engineering Contradiction:

Improvecage weightVSAvoidcage orientation

Core Design Contradiction:

Weight of moving objectVSStability of the object's composition

Solution Approach 1:

The cage design adapts to dynamic eccentric rotation conditions by using multiple guiding protrusions that can accommodate radial and axial movements. The rounded surfaces of the protrusions allow the cage to dynamically adjust its position while maintaining stable orientation, preventing tilt during high-speed eccentric operation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The cage incorporates balancing features through its guiding protrusion arrangement that counteracts the centrifugal force-induced tilt. The symmetric distribution and geometric design of the protrusions create counterbalancing moments that prevent the cage from tilting under centrifugal loading during eccentric rotation.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Prevents high surface pressure contact and cage tilting, ensuring stable lubrication and reduced frictional torque, while maintaining durability and ease of assembly.

Implementation Method 1

the circular annular portion has, on an outer periphery of the circular annular portion, an outer ring guiding surface configured to come into sliding contact with the one of the outer ring groove shoulders

Methodology Applied

Scientific EffectSliding contact: Friction

Implementation Method 2

due to the tilt of the cage caused by the centrifugal force due to eccentric rotation

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentUS20260016049A1Ball bearing with an outer ring-guided cage and an eccentric rotation device

Publication Date: 2026.01.15 NTN CORP

AI summary

A ball bearing with an outer ring-guided cage is provided. The outer ring-guided cage is a crown-shaped resin cage including a circular annular portion disposed radially inward of one of outer ring groove shoulders so as to be opposed to the one outer ring groove shoulders; and a plurality of pillars having a cantilevered structure, and axially extending from the circular annular portion. The circular annular portion has, on its outer periphery, an outer ring guiding surface that comes into sliding contact with the one outer ring groove shoulder. Each pillar includes an outer ring guiding protrusion that comes into sliding contact with the other outer ring groove shoulder.