Bearing Cage Structure for Umbrella Effect and Grease Flow

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Solution Overview

Problem

High-speed rotation of ball bearings leads to an 'umbrella effect' where cantilever portions flex radially outward due to centrifugal force, causing increased friction and potential failure, and existing lubrication systems are inefficient in managing grease distribution, leading to performance deterioration.

Innovation Solution

A bearing cage design with a thicker annular backbone and reduced material in cantilever portions, featuring recesses and grooves that store and redistribute grease, reducing centrifugal force and enhancing lubrication by allowing smooth grease flow between rolling elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the cantilever portions are made thinner to reduce material, then the umbrella effect is reduced, but the structural strength decreases

Engineering Contradiction:

Improveumbrella effectVSAvoidstructural strength

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The bearing cage is made of a composite material comprising a thermoplastic matrix and a reinforcing filler, providing both reduced density (to reduce centrifugal force and umbrella effect) and enhanced mechanical properties (to maintain structural strength).

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The backbone portion is designed with a greater radial thickness than the cantilever portions, concentrating material where structural strength is most needed while keeping the cantilever portions thinner to reduce the umbrella effect.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If the cantilever portions are made thinner to reduce the umbrella effect, then friction is reduced, but the cage becomes more prone to cracking

Engineering Contradiction:

ImprovefrictionVSAvoidcage cracking resistance

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The composite material comprising thermoplastic matrix and reinforcing filler provides both reduced density for lower friction and enhanced mechanical properties for improved cracking resistance.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The cage is subjected to heat treatment after molding to relieve internal stresses and prevent cracking during high-speed rotation, addressing potential reliability issues before the cage is put into service.

Inventive Principle:

Principle #10Preliminary action

3Strength

If the backbone portion is made thicker to maintain structural strength, then the cage can withstand centrifugal force, but the device complexity increases

Engineering Contradiction:

Improvestructural strengthVSAvoidcage structure complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The radial thickness of the backbone portion is optimized within a specific range (0.05 to 0.15 times the outer diameter of the rolling elements) to provide sufficient structural strength without excessive complexity.

Inventive Principle:

Principle #35Parameter changes

4Device complexity

If conventional lubrication systems are used, then the system is simple, but grease distribution is inefficient leading to performance deterioration

Engineering Contradiction:

Improvelubrication system complexityVSAvoidbearing performance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The recesses in the cantilever portions automatically capture and store grease, allowing the lubrication system to self-regulate grease distribution without additional complex mechanisms, while ensuring reliable lubrication at high speeds.

Inventive Principle:

Principle #25Self-service

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

The design significantly reduces the 'umbrella effect' and improves lubrication, resulting in enhanced bearing performance and reduced heat generation during acceleration and deceleration, while maintaining structural strength and preventing cage cracking.

Implementation Method 1

High-speed rotation of ball bearings leads to an 'umbrella effect' where cantilever portions flex radially outward due to centrifugal force

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentUS11655853B2Bearing cage and bearing

Publication Date: 2023.05.23 AB SKF SKF PATENT DEPARTMENT

AI summary

The present disclosure provides a bearing cage and a bearing. The bearing cage comprising: a generally annular backbone portion having a front side and an opposite back side; a plurality of cantilever portions extending from the front side of the backbone portion in an axially forward direction of the bearing cage, the cantilever portions being arranged along a circumference of the annular backbone portion, defining a plurality of pockets bearing, wherein the backbone portion has a radial thickness which is larger than that of the plurality of cantilever portions. Each of the plurality of cantilever portions comprises two prong portions and a connection portion between the two prong portions. The bearing cage further comprises one or more of: a plurality of recesses formed in a radially outer side of the cantilever portions, and a plurality of grooves formed in the radially inner side of the bearing cage.