Snap-Joint Two-Part Bearing Cage for High-Speed Stability

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Solution Overview

Problem

Existing one-piece polymer cages in rolling bearings suffer from the 'umbrella effect' at high speeds, causing cage bars to bend and potentially rub against rolling elements or the outer ring, limiting bearing speed, while two-piece cages are either expensive or unsuitable for high-speed operation due to centrifugal forces.

Innovation Solution

A two-piece bearing cage design with identical or different cage parts connected by snap joints, featuring bars and bar receptacles that form pockets for rolling elements, with each bar having a claw and connection portion to secure the cage parts together, preventing bending and ensuring stability at high rotational speeds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If one-piece polymer cages are used, then the cage is inexpensive to make and easy to mount, but the cage bars bend radially outwards at high speed due to centrifugal force (umbrella effect)

Engineering Contradiction:

Improvecost to make and mountVSAvoidcage bar straightness at high speed

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The cage is divided into two separate halves that are connected by retaining elements (rivets). This segmentation allows each half to be structurally optimized to resist centrifugal forces while maintaining ease of manufacture. The two-piece construction eliminates the umbrella effect by providing rigid support against radial bending.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cage combines different materials: polymer cage halves with metal retaining elements (rivets). This composite approach provides the benefits of polymer (cost-effectiveness, ease of manufacture) while incorporating metal components (high strength, rigidity) to prevent bar bending at high speeds.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If stamped steel two-piece cages are used, then the cage is inexpensive to make and easy to assemble, but it is not suitable for high-speed operation due to centrifugal forces

Engineering Contradiction:

Improvecost to make and assembleVSAvoidoperational speed

Core Design Contradiction:

Ease of manufactureVSSpeed

Solution Approach 1:

The cage uses polymer for the cage halves (lightweight, suitable for high speed) combined with metal rivets (strong retaining elements). This composite construction achieves both cost-effectiveness and high-speed capability, overcoming the limitation of all-metal stamped steel cages.

Inventive Principle:

Principle #40Composite materials

3Speed

If metal or fiber reinforced phenolic resin two-piece cages are used, then the cage is suitable for higher speeds, but it is expensive to make and not easy to rivet

Engineering Contradiction:

Improveoperational speedVSAvoidcost and difficulty of assembly

Core Design Contradiction:

SpeedVSEase of manufacture

Solution Approach 1:

The retaining elements (rivets) are designed with specific geometric parameters - a head portion and a shank portion that fits into recesses in the cage halves. This parameter optimization enables automated riveting processes, making assembly easier and more cost-effective while maintaining high-speed performance.

Inventive Principle:

Principle #35Parameter changes

4Device complexity

If one-piece polymer cages are used, then the cage structure is simple, but the cage bars are subjected to centrifugal force causing bending and potential rubbing

Engineering Contradiction:

Improvecage structureVSAvoidprevention of rubbing

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

Dividing the cage into two halves connected by rigid retaining elements creates a more reliable structure that prevents bar bending and rubbing, while keeping the overall design relatively simple through the use of identical or complementary cage halves.

Inventive Principle:

Principle #1Segmentation

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 allows for high-speed operation without the umbrella effect, is cost-effective to manufacture and assemble, and provides a stable connection between cage parts, making it suitable for applications like electric vehicles, while being easy to inspect and maintain.

Implementation Method 1

each connection portion of one cage part is configured to snap into the corresponding claw of the other cage part such that each connection portion and its corresponding claw form a snap joint

Methodology Applied

Scientific EffectMechanical Fastener: Mechanical Fastener

Implementation Method 2

At high speed the bars bend radially outwards. This is known as the 'umbrella effect'. The bending of the bars can change the pocket geometry and may lead to rubbing of the cage bars against the rolling elements and/or the outer ring

Methodology Applied

Scientific EffectCentrifugal Force: Centrifugal Force

Data Source

PatentUS12092158B2Two-part bearing cage for a rolling bearing

Publication Date: 2024.09.17 AB SKF SKF PATENT DEPARTMENT

AI summary

A two-part bearing cage for a rolling bearing includes a first cage part and a second cage part. Each cage part includes an annular base body with a plurality of bars extending axially from the annular base body and/or a plurality of complementarily designed bar receptacles. The bars of one cage part engage in the bar receptacles of the other cage part to form cage bars for defining cage pockets configured to receive the rolling elements of the rolling bearing. Each bar includes a claw and each bar receptacle includes a connection portion such that each connection portion and its corresponding claw form a snap joint.